In doing broader research on three species of Strobeus that occur within the Glenshaw Formation in Western Pennsylvania, I have discovered many excellent plates by former authors. These plates are miniature works of art, capturing details of these fossil gastropods that may not be available in photographs. This can be a mixed bag, as authors would fill in or make-up details that didn’t exist. You’ll often see the overdrawn outlines that show what the specimen looked like if it remained in perfect shape.

Many of these specimens do not have correlating identification numbers, so finding the originals can be next to impossible. Some rare examples do exist, such as when an author illustrates a holotype. This text will review two of these historical plates. The first plate we will examine is one by Charles A. White, published in 1884, as part of a report on the fossil fauna of the “Coal Measures” (Pennsylvanian) in the state of Indiana. The second will be a plate by George H. Girty in 1915 as part of his report on the fossil fauna of the Wewoka Formation of Oklahoma.

White’s Plate 34 from the Year 1884

Plate 34 in White’s report on the Fossils of the Indiana Rocks, No. 3 is a very good representation of fossil gastropods that are known today under the genus Strobeus. All specimens on the plate were assigned to the genus Solenisus Meek and Worthen 1860, with the majority assigned the subgenus Macrocheilus Phillips 1841.

White wrote that the assignment within the subgenus Macrocheilus was confusing. Adding to this confusion, some unknown printing error reversed the genus and subgenus names for Soleniscus (Macrocheilus) on this particular plate. This mistake made correlation a little difficult at first, as I was only using the plate. The mistake is not replicated on Plate 8 of Proceedings of the United States National Museum, Volume 6, 1883, which was a loaned version of Plate 34.

Still, White’s base genus for all these was Soleniscus, a situation that Knight proclaimed was the root of many problems across the family, the Subulitidae. In his own words: “For example, differences of opinion as to the true characters of Soleniscus typicus Meek and Worthen formed the basis of several misunderstandings“. Figures 18 and 19 on the following plate represent the type species of Solenisus, Soleniscus typicus.

Plate 34 from the fauna of the Indiana Coal Measures. Published by the Indiana Geological Survey in 1884. Many examples of what is known today as the fossil gastropod Strobeus are shown.
Plate 34 from Fossils of the Indiana Rocks Coal Measures, published by the Indiana Geological Survey in 1884, shows many examples of what is known today as Strobeus.

Later Authors’ Interpretations of White’s Identifications

Between Girty (1915) and Knight (1931), most of White’s figures were reassigned to other species and all but one belong to a new genus in modern times. White was very specific when discussing his doubts about the taxonomic assignment for his figures. For example, he mentioned that Soleniscus (Macrocheilus) fusiformis, S. (M.) newberryi, and S. (M.) planus would be difficult to compare, even with full collections of all three. Knight (1931) placed all of White’s figures of these three species under Soleniscus (Macrochilina) regularis. White also had doubts about his identification of figures 13 and 14, S. (M.) texanus, and figures 15 and 16, S. (M.) medialis. Girty correlated figures 13 and 14 to S. primogenius and Knight places figures 15 and 16 under the same.

Girty (1915) considered Soleniscus ponderosa from this plate to be a synonym of Sphaerodoma primigenius [sic] by suggesting that they are the same species. He also felt the same about S. texanus, as it had been considered a younger (i.e., juvenile) S. ponderosa. Knight discusses S. ponderosa as being one of the largest examples of S. primigenius [sic] yet recovered.

Knight (1931) split White’s Macrocheilus (Soleniscus) ventricosus into two species, with figure 11 going to S. primogenius and figure 12 assigned to S. brevis. White (1881) had created the species S. brevis earlier but did not mention it in the 1884 publication. With the size of these publications and the technology to publish at the time, it is possible that his new species was not under consideration when making the plates. Figures 18 and 19 are copies of the holotype of Soleniscus typicus, thus retaining their name which is still valid today.

Girty (1915) assigned these species under the genus Sphaerodoma Keyes. Knight (1931) went full circle and reassigned species under Soleniscus (Macrocheilus) once again. It would be interesting to know if Girty and Knight had discussed the matter. They both did very large reviews that included these species, but 16 years apart. Knight was reviewing the Subulitidae, whereas Girty was reviewing the entire fossil fauna of the Wewoka Formation of Oklahoma (353 pages worth). He dedicated 23 entire pages to Sphaerodoma.

Stated Species by White in 1884FigureKnown Today As
Soleniscus? (Macrocheilus) ponderosus1-2Strobeus primogenius
Soleniscus? (Macrocheilus) primigenius3Strobeus primogenius
Soleniscus (Macrocheilus) fusiformis4-6Strobeus regularis
Soleniscus (Macrocheilus) newberryi7-8Strobeus regularis
Solenisus planus9-10Strobeus regularis
Soleniscus (Macrocheilus) ventricosus11Strobeus primogenius
Soleniscus (Macrocheilus) ventricosus12Strobeus brevis
Soleniscus (Macrocheilus) texanus13-14Strobeus primogenius
Soleniscus? (Macrocheilus) medialis15-16Strobeus primogenius
Soleniscus (Macrocheilus) paludinaeformis17Strobeus paludinaeformis
Solenisus typicus18-19Solenisus typicus
Table 1.—Correlation of species by White in 1884 with modern genus assignments.

Girty’s Plate No. 24 from the Year 1915

In 1915, Girty published a monograph of the fossils of the Wewoka Formation of Oklahoma. In the publication, he provided 35 well-detailed fossil plates. The publication was very long, weighing in at 353 pages. Having been published over 100 years ago, it is no surprise that all the species represented on plate XXIV (24) now have new generic assignments. Knight (1931) reassigned most to the genus Soleniscus (Macrocheilus) again, restoring the genus and subgenus White (1884) had used. Over the intervening years, most of these species continued to change generic names, identifiable as Soleniscus, Polyphemopsis, Sphaerodoma, StrobeusIanthinopsis, and back to Strobeus again after a paper by J. Harper in 1981.

Plate 24 by Girty in 1915.
Plate 24 from Fossils of the Wewoka Formation of Oklahoma, published by the U. S. Geological Survey in 1915.

In figure 13, Girty includes a copy of Conrad’s illustration of Plectosylus primogenius on his plate for use in comparison. Knight agreed with Girty’s figures 14-17. Knight placed Girty’s figures 9 through 12 of S. brevis under S. primigenius and placed figure 8 as Auriptygma simplex. Additionally, Knight correlated figure 4 S. ventricosa and figure 7 S. brevis var as S. paludinaeformis. He placed S. ventricosa under S. paludinaeformis after examining the type specimens which were both authored by James Hall. He concluded that the only clear difference was their size.

Knight placed figure 8 under Auriptygma simplex. Later in 1936, he changed all North American specimens that were placed under Auriptygma to a new genus, Leptoptygma. He was enlightened after taking a trip to Europe to view many genotype specimens. Knight was better informed on the relationship between North American specimens and their European counterparts since he was able to study them in person.

Hall (1858) created three new species under the genus Macrocheilus. M. fusiformis, M. ventricosus, and M. paludinaeformis. I’ve included a few figures from Hall’s plate in a graphic below. You can get a rough idea of why Knight (1931) combined M. ventricosus and M. paludinaeformis. Knight concluded that M. paludinaeformis was an adult specimen whereas M. ventricosus was a juvenile of the same.

Girty considered both S. ponderosa and S. texanus to be junior synonyms of S. primogenius. He felt that S. texanus was a younger S. ponderosa (=S. primogenius). Girty’s identified figures of S. primogenius are still considered to be of that species today. The age of the specimen came into consideration for both figures 4 and 7. Knight (1931) placed both of these under S. paludinaeformis, as he considered them to be juveniles.

Sphaerodoma intercalaris from figures 1 and 2 is known today as Strobeus intercalaris. Sphaerodoma gracilis, figure 3, is known as Soleniscus gracilis.

Stated Species by Girty in 1915FigureKnown Today As
Sphaerodoma intercalaris1-2Strobeus intercalaris
Sphaerodoma gracilis3Soleniscus gracilis
Sphaerodoma ventricosa4Strobeus paludinaeformis
Sphaerodoma paludiniformis5-6Strobeus regularis
Sphaerodoma brevis var.7Strobeus paludinaeformis
Sphaerodoma brevis8Leptoptygma simplex
Sphaerodoma brevis9-12Strobeus primogenius
Sphaerodoma primigenia13-17Strobeus primogenius
Table 2.—Correlation of species by Girty in 1915 with modern genus assignments.

References