Notes on a Few Silurian Fossils from Ayrshire. 167 



ORDER PHYLLOPODA. 

 Genus Solenocaris — J. Young, 1868. 



(Proc. Nat. Hist. Soc. Glasgow, i., p. 171.) 



Solenocaris solenoicles, J. Young. 



S. solenoides, J. Young ; loc. cit, pp. 171-173, 1. 1, f. 7, a and h. 



Ohs. — Several fragments of this peculiar crustacean are in 

 the cabinet of Mrs Gray, by whom it was originally dis- 

 covered. They do not, however, throw any additional light 

 upon its structure. 



Loc. and Horizon. — Balcletchie, south-east of Girvan, in 

 rocks of Silurian age ; exact horizon not yet determined. 



Genus Pinnocaris, gen. nov. 



Gen. Chars. — Carapace bivalve, bent along the middle line ; 

 each half is pinnaform, much attenuated towards one ex- 

 tremity ; dorsal margin almost straight, but rising at a little less 

 than a third from the rounded end into a kind of false umbo ; 

 ventral (? lateral) margin elongately sigmoidal ; the expanded 

 end of the carapace is broadly but gradually rounded ; attenu- 

 ated end produced into a long, narrow rostrum or beak, 

 truncated at its extremity; substance probably very thin ; 

 surface striated parallel to the curved margins. 



Ohs. — I have given the above name to a very peculiar fossil 

 in Mrs Gray's collection, from the resemblance each half 

 bears to the genus Pinna. The general outline is that of a 

 small Pinna, so much so, indeed, that I hesitated whether to 

 regard them as a species of Pelecypoda (Lamellibranchiata) 

 near the genera Pinna, Pteronites, or Avictclojnnna, or as 

 the carapace of a phyllopodous crustacean, allied to Ccratio- 

 caris, Discinocaris, and other like forms. In their present 

 state the specimens appear as black, flattened, shining bodies, 

 the produced and truncated end retaining more of the original 

 convexity than the other portions. On analysing the various 

 characters of these fossils, for, or against their crustacean 

 nature, we find that in support of the latter view we have the 

 absence of any definite separation into anterior and posterior 

 ends, as in a bivalve shell ; secondly, the nature of the project- 

 ing part of the dorsal margin, here called the false umbo, which 



