ifyy 



PLATE XXI.— Continued. 

 Pleueotomakia disjuncta. 



Page 84. 

 Fig. 18. The only specimen of the species yet known, showing the surface oharactei-s over most of the 

 shell. The outer volution is ilisconnected from the jn-eceding near the aperture, hut this may 

 be the result of extreme compression. 



Pleckotomaria LtrciNA var. perfasciata. 



Page 83. 

 Fig. 19. The lower surface of a specimen, showing the strong concentric, fasciculate strise of the upper 



surface continued across this part of the shell 

 Pig. 20. The upper surface of the same, presenting the usual features of the species on the smaller volution, 



but showing stronger concentric striie on the larger volution. The specimen is obliquely 



compressed so as to destroy the i-otundity of form. 



Plecrotomaria planidorsalis. 



Page 82. 

 Pigs. 21, 23. The under and upper surfaces of a specimen which is obliquely compressed, and having the 

 spiral band nearly obliterated. 



