﻿170 UETKROSTIUCI. 



Palseaspis americana. Claypole. 



1 v< 4. Pahra.pis americana (? and P. bitruncata), E. W. Claypole, Amer. 



Naturalist, vol. xviii. p. 12:24. 

 1885. Pakeaspis americana, E. W. Claypole, Quart. Journ. Geol. Soc. 



vol. xli. p. 62, woodc. fig. 7. 

 (?) 1885. Palccaspis bitrancata, E. W. Claypole, ibid. p. 62, woodc. 



fig. 8. 



Type. Imperfect dorsal shield ; Museum of Buchtel College, Akron, 

 Ohio. 



A species known only from imperfect specimens, as yet incapable 

 of precise definition, but apparently distinguished from P. sericea by 

 the more regularly ovate form of the shield and the slightly more 

 obtuse rostrum. 



The form named bitruncata is not improbably the ventral shield 

 of this species. 



Form. § Loc. Onondaga Group : Perry Co., Pennsylvania. 



P. 6132. Imperfect internal cast of shield. 



Presented by Prof. E. W. Claypole, 1890. 



P. 6133. Several fragments. 



Presented by Prof. E. W. Claypole, 1890. 



Genus CYATHASPIS, Lankester. 



[Rep. Brit. Assoc. 1864 (1865), Trans. Sect. p. 58.] 



Syn. Diplaspis, G. F. Matthew, Bull. Nat. Hist. Soc. New Brunswick, 

 no. vi. 1887, p. 69. 

 Scaphaspis, E. R. Lankester, Rep. Brit. Assoc. 1864 (1865j, 

 Trans. Sect. p. 58 (in part). 



Dorsal shield oval, consisting of four separately calcified portions 

 — a large central disc, with a short azygous rostral plate anteriorly, 

 and a pair of large cornua on the sides. Orbits not completely 

 enclosed in the shield. 



In the so-called Diplaspis, and in Cyathaspis integer, the dorsal 

 and ventral shields have been found in natural association ; and a 

 Scaphasjus-shs-iped shield occurs in the same beds as the type species. 

 Until confirmatory evidence is obtained, we venture to regard the 

 transverse division of the lateral cornua in Diplaspis as accidental. 



Cyathaspis banksi (Huxley & Salter). 



[Plate IX. fig. 3.] 



1856. Pteraspis banksii, Huxley & Salter, Quart. Journ. Geol. Soc. 

 vol. xh. p. 100 ; pi. ii. fig. 2. 



