168 Proceedings of the Royal Physical Society. 



in no way appears to partake of tlie characters of the umbo 

 in the Pelecypoda; thirdly, the presence of the object, indi- 

 cated at a, Fig. 3, which, although without organic connection 

 with the carapace near it, is, I believe, one of the telson 

 spines, similar to those of Ceratiocaris, and other genera; 

 fourthly, the lines of growth instead of graduating outwards 

 from the projecting point of the dorsal margin, as the similar 

 strise do on the valve of a shell (bearing in mind that the 

 umbo of a bivalve is its " initial point "), appear to me to be 

 much more regularly concentric (or as we see them, semi-con- 

 centric) round a central point or apex, as would be the case 

 if both valves were spread out, similar to the genera Discino- 

 caris or Peltocaris. On the other hand, in support of the 

 molluscan affinities of these fossils, we have the general pinna 

 ov jpteronites-like form, although the larger end is more obliquely 

 rounded than is usually met with in these genera, and the 

 entire absence of the characteristic punctate ornamentation 

 seen on the carapace of many Crustacea, combined with the 

 absence of all trace of the eye-spot. It appears to me that 

 the balance of evidence is at present in favour of the crusta- 

 cean affinities of these fossils, and that they cannot be placed 

 in any of the genera known to me, such as Ceratiocaris, M'Coy; 

 Hymenocaris {Saccocaris), Salter; Physocaris, Salter; Pelto- 

 caris, Salter; Dictyocaris, Salter; Dithyrocaris, Scouler; Myo- 

 caris, Salter; Discinocaris, Woodward; Solenocaris, Young; 

 Lingulocaris, Salter ; Caryocaris, Salter ; Aptychojms, Bar- 

 rande ; Anatifopsis, Barrande ; Solenocaris, Meek (nonYoung); 

 Colpocaris, Meek; Archccocctris, Meek; Cryptocaris, Bar- 

 rande ; and Pterocaris, Barr. I have therefore, as above stated, 

 proposed for them the name Pinnocaris. As none of the 

 specimens to which I have access have the valves spread out, 

 it is impossible to say with certainty whether Pinnocaris had 

 a dorsal furrow along the back, like Peltocaris, or was devoid 

 of one, as in Discinocaris. 



I desire that my remarks on these fossils may be taken as 

 purely of a provisional character, and I shall look with much 

 interest for the discovery of further and more complete 

 examples, with the view of definitely ascertaining their syste- 

 matic position. Upon the production of further evidence of 



