136 NEW YORK STATE MUSEUM 



thickened ridge often curiously replaced and hardened by chert and 

 in several observed instances this central ridge is out of alinement 

 lying either at one side or the other of the middle line and occasionally 

 askew. Back of the anterior rostral marginal curves and close upon 

 them lie broadly rounded nodal elevations from which low grooves 

 converge backward. The lateral margins of the shield are thickened 

 like whipcord and the surface of the carapaces, when well preserved, 

 shows a fine papillose or linear ornamentation quite peculiar to the 

 species, in the sense that it is not like the linear incised or elevated 

 inosculating ornament which usually marks the fossil Phyllocarids. 



The very singular feature of this carapace is the mode of preserva- 

 tion of the nuchal margin or ring. On the surfaces of the slabs 

 this ring is exposed frequently in detached condition and it is obvious 

 that in its original state it was greatly thickened so as to strengthen 

 and assure convexity to the head shield. The single convex specimen 

 of the carapaces shows that the form in its original state was elevated 

 and broadly rounded, carrying the curvature indicated by the 

 detached rings found in the rock, and that the carapace was 

 without any evidence of median suture or independent rostrum. 



The presence of antennae is indicated in one very obvious specimen 

 and by scattered fragments of others. 



As to the thorax and abdomen, little can be said. There are 

 remains of segments which carry at each extremity a jointed append- 

 age of triangular form. So far as the evidence goes they seem to be 

 attached to the segments as lateral, terminal pieces and not to have 

 functioned as exopodites. These triangular plates lie scattered about 

 in considerable numbers and it seems from certain segmental struc- 

 tures that they are themselves related to the segmental composition. 

 Of the tail and telson parts nothing definite is now known. 



Paulocaris was a crustacean of decapod affinities. However 

 much the flattened carapaces suggest alliance to such Phyllocarids 

 as Hymenocaris and the Ceratiocaridae, the solid carapace, the 

 antennae and segments are too clearly decapodan, whatever the 

 station of the genus may prove to be within this order. 



The other species, represented in the drill core and preserved 

 in clay shale is in two specimens, both together too fragmentary to 

 serve much more than to indicate an interesting species of the ancient 

 shrimps known as Palaeocaris and Gampsonyx. In both these 

 specimens the head is missing. All that remain are portions of the 

 thorax and abdomen. The species is doubtless distinct from any 

 recorded and subject to better knowledge may be designated as 



