170 MAZATLAN UNIVALVES 



CLASS PTEROPODA. 



Omnia adJiuc ignota. 



CLASS GASTEROPODA. 



The knowledge of this class of Mollusks has rapidly increas- 

 ed since attention has been paid to their mouths and teeth. 

 The main divisions here adopted are probably well founded. 

 In the smaller sections we do not as yet know enough to 

 stereotype an arrangement. Whatever character be taken as 

 the 'guide, families are united, unlike in other respects, or 

 separated when many points of structure indicate affinity. Tht 

 science being in a transition state from the old conch ological 

 arrangements, all dogmatism, on any side, is clearly out of place. 



SUB-CLASS OPISTHOBBANCHIATA. 



ORDER TECTIBBANCHIATA. 



FAMILY CYLICHNID^. 

 GENUS CYLICHJSTA, Loven. 



221. CYLICHNA LUTICOLA, C. B. Ad. 



Bulla (Cylichna) luticola, C. B. Ad. Pan. Shells, p. 215, no. 



320: do. p. 319. 

 Haminea luticola, H. fy A. Ad. Gen. vol. ii. p. 16. 



-Shell remarkably constricted in the middle, swelling an- 

 teriorly. The surface is extremely finely decussated between 

 the well-marked striae of grewth. Long. *1, lat. '04. 



Hab. Panama ; crawling on liquid mud, near low water mark, 

 at the bottom of a steep sand beach, rare ; C. B. Adams. 

 Mazatlan ; 2 dead specimens off Chama ; L'pool Col. 

 Tablet 782 contains a characteristic specimen. 



