196 VERTEBRATE REMAINS, PORT KENNEDY BONE DEPOSIT. 



TOXASPIS Cope. 

 American Naturalist, 1895, p. 757. 



This genus was established for species of Terrapenidse (Cistudinidae) in which 

 there are four claws on the posterior foot, and a zygomatic arch. The only known 

 species is the existing T. ornata Agass. 1 A tortoise of this family left abundant 

 remains in the Port Kennedy bone deposit, but thus far no feet nor crania have been 

 preserved. It is therefore impossible to determine to which of the genera it belongs. 

 I refer it provisionally to Toxaspis, which is the most primitive in structure ; but 

 the reference is of course provisional only. The family reference is clear, since the 

 plastral articulation is preserved in several cases, showing the lysosternal character. 

 The vertebral bones of the carapace are discontinued posteriorly, permitting the 

 mutual junction of the costals. 



Toxaspis anguillulatus Cope (PI. XIX, fig. 1). [Types No. 154, 155, Mus. Acad. Nat. Sci. Phil.] 



Five fragmentary carapaces on beds of matrix, three parts of plastrons, and two 

 moulds of carapaces in matrix, represent this box-tortoise. The carapaces display 

 the characters of Terrapene clausa in the wide vertebral bones with obtuse median 

 keel which crosses the intervertebral sutures and ceases at the dermal sutures, with 

 an interruption before recommencing. 



The typical specimen consists of a carapace which lacks the first and half the 

 second vertebral scuta, and the marginals of the front and most of the left side. 

 The vertebral scuta are wider than in T. clausa, and the costals shorter. The 

 marginals bones are not recurved. The carapace is in all the specimens flattened, 

 as is usual under pressure, but the component parts are not spread apart as would 

 be the case with the existing species of the family if subjected to the same condi- 

 tions. I am therefore of the opinion that this species is of a more depressed form 

 than they. A peculiar feature of the species is the sculpture of the bones. This is 

 a close and minute, but well-marked vermiculation, the ridges becoming parallel at 

 the sutures between the bones, to which they are at right>angles. On the inferior 

 side of the free marginals the sculpture becomes punctate-honeycombed. The 

 extremital parts of the costals are furrowed longitudinally by a few sharply-defined 

 grooves, which inosculate at one or two points, and then diverge, converge, or run 

 parallel with each other to the suture with the marginals, when they cease. 



The best preserved fragment of the plastron includes parts of both hypoplastral 

 and post-abdominal bones. These display a character which I have not noticed in 

 the existing species of the family ; i. e., the femoro-anal suture extends as far 

 anteriorly as the hypoplastro-post-abclominal suture. The minute sculpture is here 

 obsolete, but there are faint grooves parallel to the anterior and median borders of 

 the hypoplastron as in the existing species. The free borders are unfortunately not 

 preserved. 



The typical carapace belongs to an individual of about the size of an adult 

 Clemmys insculpta, and therefore of larger size than any of the existing North 

 American Terrapenida3. In two carapaces of smaller size, indistinct grooves extend 

 transversely on the vertebral bones on each side of the median keel. 



1 This should evidently read major. See reference. 



