) 



PLATE 62. 



Pagf 

 Fig. 1. VlTlLlN A PU8TUL08A 41t> 



] o. Ventral valve of a large individual. 



1 6. Dorsal valve of a specimen of corresponding size. 



1 c-f Ventral, dorsal, profile and cardinal views of an individual; enlarged to three 



diameters, showing the pustules of the surface. Fig. 1 /, shows the area of each 



valve, and the cardinal process and socket plates of the dorsal valve as seen througli the 



broad open deltidium of the ventral valve. 

 1 g. Interior of a dorsal valve, showing the cardinal process, dental sockets, and median septum ; 



enlarged to two diameters. 

 1 A. Interior of a ventral valve, showing the teeth, cardinal area, and the thickening of the 



shell in the rostral cavity; enlarged to two diameters. • 



1 i. Cast of a ventral valve, showing the muscular impression and filling of the rostral cavity; 



enlarged to two diameters. 



Figs'. 2, 3. Tropidoleptus carinatus 407 



2 a. Dorsal view of a young specimen of an elongated form ; from Eighteen Mile Creek, shore 



of Lake Erie. 



2 6. c. Enlarged dorsal and ventral views of the same. 



3 a. Ventral view of a young specimen of the ordinary form. 



8 6, c. Dorsal and ventral views of young specimens of larger size than the preceding. 



3 i. Ventral view of an individual, showing finer plications than usual (erroneously printed 



fig. 4, in the t«xt on page 408). 

 3 e. Dorsal view of an individual of medium size. 



3/, ^, A. Ventral, dorsal and profile views of a specimen of the usual form and size. 

 8 i, j, k. Cardinal, ventral and dorsal views of a somewhat larger and thicke led shell. 

 3 /. Dorsal view of an unusually large individual, showing the plications bifurcating beyond 



the usual size of the shell and liecoming obsolete near the thickened margin. 

 8 m. An enlargement of the rostral portions of a spacimen, showing the area, with the broad 



triangular open foramen filled by the callus of the dorsal valve. 

 3 n, 0. Interior of a ventral valve and an enlargement of the same, showing the strongly crenu- 



lated teeth. The point of the beak and margins of the foramen, have been broken away 



or absorbed. 

 S p. r. Interior of a dorsal valve and an enlargement of the same, showing the cardinal process, 



crenulated dental sockets, the projecting processes for the attachment of the loop, and 



the median septum which supports the outer end of the loop. (See wood cut page 406, 



of text.) 

 3 *. Enlargement of a jiortion of t'le surface, showing the strong punctse. 

 8 /, u. Cast of a ventral valve and an enlargement of the same. 

 3 W; X. Cast of a dorsal valve and an enlargement of the same, showing the impression of the 



cardinal process and the cavities left by the removal of the crenulated socket plates. 



