180 



Bivalves, Conchifera. — Lam. 



TuhicolcB. — Bivalve shells, contained in a tubular sheath 

 distinct from the valves ; and which are either incrusted 

 entirely, or in part, in the sides of the sheath, or project 

 beyond it. 



Genus 1. Aspergillum. — A tubular, testaceous sheath, 

 diminishing gradually towards its fore part, where it is open, 

 and enlarging to a club-shaped form towards the other ex- 

 tremity; the club having two valves incrusted on the side of 

 its inner substance. The terminal disk of the larger end is 

 convex, furnished with subtubular foramina, and has a fissure 

 in the centre. — PL iii. fig. 21, 



Serpula penis. — Liu, 



2. Clavagella. — A tubular testaceous sheath, diminishing 

 to an opening anteriorly, and terminating behind in an oval 

 and club-shaped form, set with spiniform tubes ; the cla- 

 vated termination displaying, on one side, one valve fixed in 

 its substance, the other valve being loose in the sheath. 



Fistulana echinata, Ann. du Mus. Tom, vii ; Teredo 

 echinata, Brocch. Vol. ii. Tab. xv. fig. 1. 



3. Fistulana. — A tubular, and, most frequently, a testa- 

 ceous sheath, lessening towards its anterior end, which is 

 open, and including a loose bivalve shell, gaping when the 

 valves are united. 



This differs from the preceding tuhicolce in neither of the 

 valves of the included shell being imbedded in the substance 

 of the sheath, 



Fistui. ampullaria, Ann. du Mus. Vol, vii. p. 428. 



4. Septaria. — A very long testaceous tube, tapering in 

 its fore part, and internally subdivided by vaulted septa, 

 generally incomplete. The anterior part of the tube is 

 terminated by two other very thin tubules, not internally 

 divided. 



