28 



paratively broad, for the posterior segment has a length of 1 1-2 

 inches by a width of 3 inches. 



Found in the Waterlime group near Buffalo, N. Y. 

 CERATIOCARIS ACUMINATUS, Hall. 



This was apparently the rarest genus of all the fauna of the 

 Waterlime group. Besides the few fragments described in the 

 Palaeontology of New York, Vol. iii., p. 420*-423*, and in this 

 Bulletin, Vol. iv., p. 19, no discovery of this remarkable crus- 

 tacean has been recorded in America. The present specimen 

 (Fig. 2, Plate 3) is perfect, and presents in a lateral view a close 

 resemblance to the figures of the specimens found in England. 



The carapace of this species is described by Prof. Hall as fol- 

 lows : "Carapace somewhat rhomboid-ovate ; width a little less 

 than one-half the length ; posterior articulating margin less than 

 half the greatest width in the middle. From the postero-basal 

 margin the outline is gently curved downward for about three- 

 sevenths of the length, and then turns more abruptly upwards and 

 forwards, the anterior end terminating in an acuminate process. 

 The lateral margin is marked by a narrow raised border. Dorsal 

 margin slightly curved for three-fourths of the length, the ante- 

 rior fourth being more abruptly bent downward to the pointed 

 extremity. Surface strongly striated concentrically." 



The median line which divides the carapace into two halves, 

 can be seen in this specimen from the posterior margin of the 

 carapace to within 1-2 inch of the anterior acuminate process. 

 There are no ocular spots visible. 



The body shows five segments and the caudal appendage. 

 The first and second of these articulations are slightly imbricat- 

 ing and of almost equal size, 3-8 inch long and one inch wide, 

 with slightly rounded angles. The third articulation is twice as 

 long, tapering slightly posteriorly ; the fourth is 5-8 inch long 

 and 7-8 inch wide at its anterior, and 3-4 inch wide at its poste- 

 rior margin. The fifth articulation is the longest ; it is about 

 oblong, 1 1-4 inches long and 5-8 inch wide. The first and 

 second articulations show a surface-marking of delicate obliquel)' 

 running striae. The other articulations are apparently smooth. 



