322 



PALEONTOLOGY OF OHIO. 



what pointed in front, with the posterior margin wider, obliquely trun- 

 cated from above backward and downward, and sinuous, so as to give 

 more or less angularity to the posterior basal extremity ; basal margin 

 apparently with a kind of ridge or fold along most of its length, and 

 ascending with a slightly convex outline forward, so as to meet the dor- 

 sal margin (which is more nearly horizontal) at a rather acute angle in 

 front; eyes (if there are any) unknown; abdomen or body with the six 

 segments of nearly equal size, and strongly imbricating ; telson appar- 

 ently as long as three of the abdominal segments, flattened, of moderate 

 breadth anteriorly, and tapering behind; stylets not clearly seen, but 

 apparently one on each side of the telson. Other abdominal appendages 

 unknown. Surface of all parts smooth. 



Length of head or cephalothorax, from the anterior to the posterior 

 basal extremities, 0.34 inch; height, 0.18 inch; length of the six body 

 or abdominal segments, 0.51 inch; height, 0.16 inch; length of telson 

 unknown. 



In one of the specimens there is a leg-like appendage, seen in the 

 matrix extending close along under and parallel to the basal margin of 

 tlie head or cephalothorax. This appendage, or rather what can be seen 

 of it, consists of three joints, two long and one short. The posterior joint, 

 although apparently broken at the posterior end, is 0.13 inch long, and 

 rather stouter than the next in front of it, which is of the same length. 

 The third joint only shows a little of one end, which connects with the 

 anterior end of the forward one of the two longer joints, and is flexed at 

 right angles to the latter, so as to pass under the anterior margin of the 

 . cephalothorax. This may possibly be one of the abdominal appendages 

 bent forward, but it has more the appearance of a stout antenna bent 

 backward. Prof. Dana thinks it most probably the latter. 



In regard to the affinities of this type not much can be said without 

 better specimens for comparison. Prof. Dana suggests, however, that it 

 may possibly have some relations to the recent genus Cuma. Being 

 unable to find any defined genus to which it can be properly referred, I 

 proposed for its reception a new genus under the name Archasocaris, in 

 .allusion to the ancient period of its existence. 



Locality and position : Same as preceding. 



