126 NEW YORK STATE MUSEUM 



Thoracoceras wilsoni sp. nov. PI. 8, fig. 1-5. The discovery of 

 the species herewith presented is of more than ordinary interest, 

 not alone from the fact that it constitutes a new element in this 

 fauna, but also because of its very close relationship to 

 a form described by Whiteaves from the zone with 

 Stringocephalus burtini in the Devonic rocks of 

 Manitoba. 1 The associates of this fossil in its occurrence at 

 lakes Manitoba and Winnepegosis as reported by Dr Whit- 

 eaves are, besides Stringocephalus, some forms which pertain 

 to the middle Devonic as developed in New York, such as 

 C y r t i n a h a m i 1 1 o n e n s i s , A t r y p a reticularis and 

 var. a s p e r a , A c t i n o p t e r i a b o y d i , Paracyclas 

 e 1 1 i p t i c a , also Pent a merus c o m i s Owen, which is 

 not known to be a New York fossil, but pertains to the upper 

 Devonic horizon in the state of Iowa, and a species identified as 

 Rhynchonella pugnus Martin, a fprm already well 

 known from the upper Devonic of New York, specially in the 

 Chemung fauna at High point, Naples. <So far as the peculiar 

 generic characters of this species of Thoracoceras are con- 

 cerned, they have not heretofore presented themselves in the 

 cephalopod faunas of this state. Nor does the association of this 

 species with the fossils of the Agoniatite limestone justify the 

 construction of the fauna of the latter as in any way indicating 

 the proper geologic horizon of Stringocephalus in the New York 

 sediments. 



The shell has a slight cyrtoceran curvature, notable chiefly in 

 the distal or apertural region. The cast of the interior shows a 

 very decided prismatic appearance, there being 10 well defined 

 prism faces with flat or at times slightly concave surfaces. Of 

 these faces that on the inner curvature of the dorsal surface is the 

 broadest and is well defined over the body chamber, where the 

 other faces become faint or quite extinguished. The body cham- 

 ber shows a slight constriction at about one half its length. In 

 two of the casts in which the body whorl and aperture are 



i Descriptions of some new or previously unknown species of fossils from the Devonian rocks 

 of Manitoba. Royal soc. Can. Trans. 1890. § 4, p. 93 (100-10) pi. 4-10 (7, fig. 1-4). 



