18 PALAEONTOLOGY OF NEW YORK. 



in the limestone near the base of the Hamilton shales, at Centerfield, and in the 

 upper shales on Canandaigua hake, Ontario county. In the Tully limestone 

 at Tinker's Falls, Onondaga county; Goodwin's, Cayuga Lake, and near Lodi 

 Landing, Seneca hake. 



Dalmanites (Cryph.eus) Barrisi, n. sp. 



PLATE XVI \, FIG. IS. 



Sim.' [MENS of PYGroiA from the hull' and drab Devonian limestones in the State 

 of Iowa, present certain peculiarities which will not permit their union 

 with cither of the foregoing species. The general aspect of these caudal 

 shields is quite similar to that presented by very young individuals of Dal- 

 mani/rs Boothi, var. Calliteles, with the exception that in the latter the axial 

 spine is scarcely developed, while in the Iowa species it is conspicuous 

 and broader than any of the lateral spines. The lateral spines are long, 

 round, .-lender and terete, with a gentle backward curve; slightly thickened 

 at the base, and not elevated along the middle as in the New York species. 

 They are also relatively much larger than in any adult specimen of the var- 

 iety Calliteles observed. 



The axis of the pygidium tapers rapidly, and bears from six to eight annu- 

 lations, which have a strong forward inclination in the middle. 



All the specimens representing this species are small, hut are of about the 

 same -i/.e. and have undoubtedly attained their mature growth. The best 

 preserved of the specimens has a length of 8 mm. to the extremity of the 

 axial spine, a width of ',) mm. along the anterior margin to the bases of the 

 lateral spines; the length of the anterior spines is 5 mm. 



Distribution. Hamilton group. In the limestones usually referred to this 

 horizon near New Buffalo, and at Searstown and Iowa City, Iowa. 



