Page:Proceedings of the United States National Museum, Volume 76.djvu/139

Rh of Tuzoia that at first sight recalls the Middle Cambrian T. praemorsa and the Lower Cambrian T. spinosa. It can not be confused with T. retifera and it allies because of the presence of more marginal spines and the frill on the keel.

Comparing T. getzi with T. spinosa, beside the common possession of keel spines, we find but little chance for confusion since the latter has two sets of marginal spines. There is more resemblance to T. praemorsa both in the shape, size, and distribution of the reticulations and particularly in the scalloped frill on the keel, but right here we find an easy way to distinguish the two; T. getzi has perhaps a dozen spines or scallops along the keel while T. praemorsa has only about seven.

The specific name is given in recognition of the interest of Noah L. Getz in collecting the fossils, as rock was quarried on his farm, which resulted in the finding of this and many other fine specimens.

Horizon and locality.—Lower Cambrian, Kinzers formation; (loc. 12x) near Rohrerstown, Pennsylvania.

Holotype.—Cat. No. 10044, Peabody Museum, Yale University.

A single specimen from the Kinzers formation represents another species that should, perhaps, be referred to a new genus. The specimen is an impression of the exterior of an extremely spinose form. I am unable to decide whether this represents an entire valve, in which case it, of course, belongs to a new genus, or whether it comprises only that part of the shell between the dorsal line and the keel.

Comparing this form with the more spinose species of Tuzoia, we note first the extraordinary extension of the dorsal line into long, upturned spines such as we find in some living Crustacea. Assuming that the longer spines occur on the rear margin and that the outer edge extends only to the keel, we note the very long spine in the usual position between the dorsal extension and the keel. If this is only the inner part of the test one or more marginal spines should occur beyond the keel. At least five spines edge the anterior margin exclusive of the dorsal extension. If the foregoing interpretation of the shell is correct, then the broad-based spine along the lower margin belongs to the keel and would indicate the presence of a frill.

The specific name is given in honor of Dr. Carl O. Dunbar, of Yale University, who so kindly permitted me to describe this fossil in this study of the group to which it belongs.

Horizon and locality.—Lower Cambrian, Kinzers formation; (loc. 12x) near Rohrerstown, Pennsylvania.

Holotype.—Cat. No. 10046, Peabody Museum, Yale University.