Domatoceras Hyatt, 1891, is one of the easier-to-recognize nautiloid cephalopods in the Glenshaw Formation. If you can see a camera profile, the genus can be identified. Each chamber in the cephalopod shell is elongated toward the venter, with compression between the flanks. The siphuncle hole—where the siphuncle penetrates each chamber wall—is slightly off-center towards the venter. See Figure 2 for Hyatt’s drawing of this feature.

Suture marks on the flank make a broad, sweeping arch pointed towards the anterior end. At each revolution, the shell covers part of the previous whorl.

Figure 1.—Domatoceras, Figure 45 and 46 from Hyatt, 1900.
Figure 2.—Domatoceras camera cross-section, Figure 47 from Hyatt, 1900.