10 GENERA OF SHELLS. 



êtes ; terminal disc of the club convex, pierced 

 by numerous sub-tubular holes, with a central 

 fissure. 



It has been erroneously supposed that the asper- 

 gillum is fixed to rocks by its smaller end, which is 

 necessarily open. 



A. Javanum, vaginiferuni, Novœ Zelandiae, agglutinans. 



Clavigella. Sheath tubular, testaceous, 

 tapering and open anteriorly, and terminated 

 posteriorly by an oval, subcompressed mass, 

 bristled with spiniform tubes ; mass presenting 

 at one side one valve imbedded in its parietes, 

 the other free in the tube. 



C. cristata, echinata, tibialis, Biocchii. 



FisTULANA. Sheath tubular, generally tes- 

 taceous, more turgid and closed posteriorly, 

 attenuated anteriorly, open at summit, con- 

 taining a free, bivalve shell ; valves equal and 

 gaping when closed. 



F. clava, corniforniis, gregata, lagenula. 



Septaria. Tube very long, gradually atten- 

 uated at base, divided interiorly by vaulted par- 

 titions, anterior extremity terminated by two 

 other slender tubes, not divided interiorly. 



The septariœ are little more than large Fistulanee, and 

 scarcely deserve to be made into a separate genus. 



S. arenaria. 



Teredina. Sheath testaceous, tubular, cyl- 

 indrical, posterior extremity closed, presenting 



