.'94 NEW YORK STATE MUSEUM 



In the cephalic region are several irregular, low and smooth 

 areas, which are slightly raised above the adjoining surface of the 

 carapace and are in noteworthy contrast to it. Among these 

 nodes is a clearly defined ocular spot, which is a smooth, strongly 

 elevated tubercle with a central depression, wherein lies a small 

 lens-like convexity. This spot may be more specifically located 

 in one specimen, where it lies 10 mm from the dorsal line and 

 20 mm from the anterior extremity. The surface is ornamented 

 with fine, low, rather distant lines, spreading over the wider 

 parts of the carapace and converging to the extremities. 



Of the carapace of the species we have two specimens in black 

 shale, one a right, the other a left valve, one slightly imperfect in 

 the cephalic region, the other lacking the posterior part. These 

 are of about the same size, and the more complete measures as 

 follows: length along hinge 105 mm, median width 60, width of 

 posterior edge 38. 



Associated with these carapaces are some tail spines, in two 

 •cases attached to the distal segment of the abdomen. Another 

 last segment is somewhat better preserved, and in its flattened 

 condition is 40 mm long and 20 mm wide. The surface lines on 

 these are very fine but not latticed, as is occasionally the case in 

 Ceratiocaris. The smaller of these two specimens has the 

 three caudal spines attached, but only the right cercopod is well 

 shown, which is rather broad, flat and lanceolate, and, in com- 

 parison with specimens of the telson, quite short. A single tel- 

 son, incomplete at the base and top, has a length of 75 mm; 

 another, also incomplete at the base, is 50 mm long. These 

 telsons bear' a ridged upper surface, there being a single sharp 

 ridge on either side of the median ridge. Neither it nor the 

 cercopods bear evidence of spines or tubercles. 



Comparisons. On instituting comparisons with recorded species, 

 w^e observe that Dr Woodward's gigantic species, C. 1 u d e n s i s, 

 from the lower Ludlow mudstone near Ludlow, is known only 

 from its abdomen and tail. Its carapace doubtless far surpassed 

 O. p r a e c e d e n s in size, yet in its known parts, the relative 



