424 Illinois State Laboratory of Natural History. 



Seen from above, the shell is sharply and narrowly 

 pointed anteriorly, broadening quickly and then sud- 

 denly contracting to broaden again slightly, so that it 

 is widest back of the middle, from which it slopes grad- 

 ually to the somewhat bluntly pointed posterior part. 



Seen ventrally (Fig. 1), the lateral depressions show to 

 greater advantage, appearing as two constrictions ; one 

 just posterior to the middle, the other considerably an- 

 terior to it. 



Muscle impressions (Fig. 2) four, elongate-oval, situ- 

 ated at the bottom of a circular lateral depression, their 

 longest axes parallel to that of the shell and to one 

 another. 



As with L. neocomensis and L. stationis, the first an- 

 tennee (Fig. 5) have a long, narrow terminal seg- 

 ment about seven times as long as wide, armed api- 

 cally with three equal setse, one of which is cleft 

 apically for about a third of its length, having the 

 appearance of a "sense seta," the inner branch being 

 about half the length of the outer. In other respects 

 the antenna? are the same as in other described species. 



The second antennae seem armed in no especial way. 

 The three terminal spines are strong, plain, and much 

 curved, the two longer being equal in length and four 

 times the length of the apical segment; the other, seta- 

 like, and about an eighth shorter. "Urticating setas" 

 two-segmented, reaching to the middle of the terminal 

 spines. All of the inner setse blunt and spine-like. 



The palp of the mandible is short and plump. Maxillae 

 not especially armed in any way ; outer edge of the base 

 smooth. 



The first of the three pairs of feet is the shortest, the 

 others increasing in length in regular order backwards. 

 All are armed similarly, with a few slight exceptions. 

 The terminal claw of the first foot is slightly longer 

 than the last two segments taken together; the spine- 

 like seta on the inner apical edge of the second segment 



