PALEONTOL0GIC CONTRIBUTIONS 93 



Measurements. Length of specimens 6 to 8 mm, width of same 

 2 to 3 mm. 



Horizon and locality. Pittsford shale, Pittsford, N. Y. 



Observations. The specimens, ten in all, were collected by 

 Prof. George H. Chadwick and Mrs C. S. Phelps in the gray Salina 

 shale, underlain by green and red shale in the bank of the Erie 

 canal, just west of the Pittsford bridge. They are small and com- 

 pletely flattened out, but notable for their very favorable preserva- 

 tion in the very fine-grained shale, retaining features but rarely 

 seen in specimens of Ceratiocaris. This is especially true of the 

 rostrum which is seen in no less than four specimens, while Rupert 

 Jones and Woodward could figure in their Monograph of the 

 British Palaeozoic Phyllopoda, where many species of Ceratiocaris 

 are described, but one imperfect rostrum of a large species. Like- 

 wise the abdomen and telson retained in three of the ten specimens 

 are by no means often seen in Ceratiocaris. 



All the specimens figured show a distinctly outlined, rather large, 

 smooth, elevated area near the front which we have considered 

 an eye spot, although we believe it possible that it may be an 

 attachment area of an adductor muscle. Ceratiocaris does not 

 possess an eye spot or tubercle and Woodward separated Eminelczoc 

 from Ceratiocaris partly for this reason. Doctor Clarke has 

 already described a very large carapace of Ceratiocaris from the 

 black Pittsford shales 1 and there tentatively proposed the sub- 

 genus Limnocaris for valves with eye spots but otherwise like 

 Ceratiocaris, his species C. praecedens being such a form. 

 The type before us would also be referable to this subgenus, but it 

 exhibits still other features not known in typical species of 

 Ceratiocaris, namely, the posterior fringe and the short abdomen 

 which is quite surely composed of less segments than are found in 

 Ceratiocaris. It is therefore possible that this peculiar and interest- 

 ing little crustacean will in time be made to represent still another 

 subgroup of Ceratiocaris. 



The Ceratiocaris. praecedens, also occurring in the 

 Pittsford shale, is not only much larger, but differs also in its 

 relatively wider valve, which is widest in the middle and in the 

 obliquely and sinuously truncated posterior extremity of the valve. 



C. (Limnocaris) salina is associated in the gray shale 

 bed with ostracods of the Isochilina type and fragments of 

 Emmelezoe. 



1 Rep't N. Y. State Pal. for iooo, p. 92. 1901. 



