198 



REPORT ON THE STATE CABINET. 



Fig. 1. 



in obtuse processes which have some similarity with the bases of crural 

 processes in Orthis, but have more analogy with the Terebratulidge. 

 These processes are sometimes clearly broken at their termination, but 

 are often smooth as if the roughened surface had been cicatrized during 

 the life of the animal. Below these forks of the process there is a 



narrow median crest or septum which 

 reaches beyond the middle of the valve, 

 and sometimes nearly to the front. From 

 the limbs of the thickened divergent pro- 

 cesses there proceed slender crura, which, 

 at first bending slightly outwards, send 

 off" a short spur into the ventral cavity and 

 are thence directed foi'wards, and gently 

 curving, join the median crest, to which 

 they are attached, forming a loop of pecu- 

 liar character. The occlusor muscular impressions have rarely been seen 

 with any degree of distinctness ; but the depressions just at the termina- 

 tion of the crural processes, and on each side of the median ridge, are 

 striated ; and this striation often ^ „ 



' Fig 2. 



extends in a wide flabelliform s / / 



margin, the interior of both 



valves is strongly pustulose. In the accompanying wood-cuts, fig. 1 

 represents the interior of the dorsal valve, and fig. 2 a longitudinal sec- 

 tion of the valve ; /, cardinal process ; J, crenulated teeth-sockets ; c, 

 crural processes ; I, loop ; s, septum. 



In the punctate texture of this shell, it differs from either of the 

 Genera Lept^na, Strophomena or Strophodonta ; but this might not be 

 an objection to admitting Tropidoleptus into the family, were the other 

 characters coincident. The area is longitudinally striated, and presents 

 a different aspect from any of the Strophomenid^, but has analogy with 

 some of the Orthides. The teeth are not extensions of the lamellae 

 bounding the foramen, but distinct from it and deeply crenulate or lobed, 

 and inserted into corresponding crenulate sockets in the dorsal valve. 

 The form of muscular impressions, so far as known, is not very dissimi- 

 lar to those of Strophomena or Orthis. 



In comparing the form of the cardinal process and its appendages, we 

 shall find it almost entirely similar to that of the Leptoccelia, as shown 



