CONCHIFERA. 



259 



G. modiolina is the English species, found principally at 

 Torbay. 



Clavagella. Lam. — Shell, valves very small, the one 

 being attached to the exterior, the other free 

 in the interior of the tube, which is narrow 

 and open at one end, club-shaped and spiny 

 at the other. Animal having a sack-formed, 

 closed mantle, the front with a small cleft, 

 from which projects the point of the small 

 vermiform foot, and ending behind in two short, entirely 

 connected siphons, the connecting part having a fringed 

 edge and the mouths of the siphons beset with simple 

 cirrhi; the mantle is on the lower side very thick and 

 fleshy, and still has a small opening at the origin of the 

 siphons, like Aspergillum, and Pholadomya ; the mouth has 

 four lengthened, lunar, somewhat curved tentacula ; on 

 each side is a single, thick, striped gill, which behind is 

 joined with that of the contrary side, and has above a 

 small appendage, which can only be compared to a second 

 gill. — Several species ; also fossil. 



There are very few recent specimens of this shell: some 

 have been brought from the Australian and Polynesian 

 islands, also from the Mediterranean ; one living indivi- 

 dual from the bay of Guayaquil. They perforate stones, 

 corals, and even other shells. 



Aspergilltjm. Lam. (Arytaena, Oken ; Clepsydra, 

 Schum.) — Shell, a tube resembling the spout of a watering- 

 pot, being thicker at one end than the other, the smaller 

 one open, and the larger one closed by a plate, which 

 is perforated with small holes; valves situated outside 

 near the plate, the tube terminated by several smooth un- 

 dulations, like frills. Animal having an entirely closed 

 mantle, which has only behind, two openings for the 



S 2 



