408 PALAEONTOLOGY OF ILLINOIS. 



The abdomen is more than half the length and about two-thirds the breadth 

 of the widest part of the carapace. It shows five short segments and apparently 

 part of another, the first of which is a little smaller and the second a little 

 larger than the others. None of them, however, are more than one-fifth as long 

 as the breadth of the abdomen. 



The caudal appendages being unfortunately bent down and crushed, it is not 

 possible to make out the form of the telson or the details of the other parts, 

 though the whole together seem to have been wider than the abdomen, and as 

 wide as the carapace. No surface sculpturing can be clearly made out, though 

 there is some appearance of a few irregular scattering granules near the mar- 

 gins of the carapace. (Other parts unknown.) 



It will be observed, from the foregoing remarks, that our specimen shows 

 no traces of the central spine or beak, extending forward from the anterior ex- 

 tremity of the carapace, nor of the longitudinal carina connected with it, which 

 constitutes such a marked feature in Anthapalsemon. It is possible, however, 

 that this character may have been obliterated in breaking open the concretion 

 since our specimen only shows an impression of the under side of the carapace, 

 while the appendage alluded to projects forward from the upper side, and may 

 consequently be imbedded in the other half of the concretion, which we have 

 been unable to obtain. Still, as it is possible that this appendage may be want- 

 ing in our fossil, we should not be surprised if it would prove to belong to an 

 allied but distinct genus. 



Specifically, at least, it differs from A. Grossavii, of Salter, in the propor- 

 tionally much shorter joints of the flagella of its outer antennas and the oblique 

 articulations of the segments of their peduncles ; while the latter, as well as the 

 surface of other parts, are without any traces of the fine pitting represented by 

 Mr. Salter's figures. Our specimen also shows traces of what appear to be 

 squarely truncated basal scales to the outer antennas, about as long as their first 

 joints, while Mr. Salter's figure (1) represents apparently a triangular scale 

 over one of the antennae. 



Length from the end of the caudal extremity to the anterior margin of the 

 carapace, 1 inch. Length of carapace, 0.60 inch; breadth of do., 0.43 inch. 

 Length of abdomen, about 0.30 inch; breadth of do., 0.27 inch. Length of 

 caudal appendages, 0.10 inch. 



Locality and position: Same as preceding. 



