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Order 6. CIRRHOBRANCHIATA. 



Branchias ; two equal tufts of soft, flexible, club-shaped cirrki. 



According to the observations of two most eminent French naturalists, 

 M. De Blainville and M. Deshayes, the branchiae of a very anomalous 

 genus of mollusks known as the Dentaliadce, or Tooth- shells, are a couple 

 of tufts of soft, flexible, club-shaped, cirrhus-like filaments, one on each 

 side of the animal's head. An English naturalist, Mr. Clark, who has de- 

 voted a life to the anatomy of the mollusca of our southern shores, has 

 declared that these tufts are not branchise, but salivary glands, and that 

 what M. Deshayes calls the lobes of the liver are the branchias. Should 

 this observation be confirmed, the name of our Order must be changed. 

 We have only one genus to record — - 



Dentalium. 



Genus 1. DENTALIUM, Linnceus. 



Animal ; elongated, attached to the shell near its hinder extremity ; 

 head rudimentary, eyeless and without tentacles, cirrhated on 

 the lip ; mantle circular, thick and fleshy in front, thin pos- 

 teriorly, capable of investing the entire frontal part of the body ; 

 foot placed centrally and anteriorly, consisting of a pointed cone, 

 flanked by two symmetrical side-lobes mounted on a long pedicle. 

 (Forbes.) 



Shell ; tubular, regular and symmetrical, smooth or fluted, and 

 more or less curved, attenuated posteriorly, open at both ends, 

 anterior aperture, which is tJte larger, simple and generally 

 oblique; posterior also simple, sometimes slit on the convex 

 side. 



The Dentalium embraces a curious compound of affinities. It is a gas- 

 tropod partaking of the characters of the Limpet ; its shell may be likened 

 to that of a smooth or fluted Fissurella pushed out, by a stretch of the 

 imagination, telescope-fashion, into a curved tube. It has the conical foot 

 of some of the bivalves ; and as if presenting a passage to those headless 

 mollusks, the head of Dentalium exists only in a rudimentary form, with- 

 out tentacles or eyes. Again, there are traces of affinity with the Anne- 

 tides. Apart from the consideration of the tubular form of the shell, 

 which induced both Cuvier and Lamarck to class Dentalium with the 



