316 



2. Ch^ena annulata. B.M. 



Choena annulata, Gray, Proc. Zool. Soc. 1858. 

 Hab. Mozambique ; Mauritius. 



Subfamily 2. GastrocHcENAINA. 



The tube irregular, attached. The animal living in holes in rocks, 

 shells, and other marine bodies. 



Lamarck described the shells of these animals as Gastrochcena, 

 and the tubes mixed with the tubes of a species of Pholadidce as 

 FistulancB. The shape of the tube is modified by the substance in 

 which they happen to be imbedded or attached. Sometimes the 

 animal attaches itself to a thin marine body which does not admit of 

 the animal burying itself into it ; it then forms a tube on the surface, 

 to cover the part of the body which would be exposed. 



2. Gastrochcena. 



Valves ovate, ends rounded ; tubes enclosed in a cavity, or attached 

 to the surface of shells, irregular, retort-shaped ; siphonal aperture 

 compressed, simple ; cavity simple. 



1. Gastrochcena hians. B.M. 



Pholas hians, Chemn. x. t. 172. f. 16/8. 

 Gastrochcena Sprenylex, Nov. Acta Dan. ii. f. 8, 11. 

 G. cuneiformis, Lamk. no. 1 ; Sow. Gen. f. 3-5. 

 Hab. Isle of France. 



2. Gastrochcena modiolina. B.M. 



Gastrochcena modiolina, Lamk. no. 3 ; Sow. Gen. f. 1, 2. 

 Mya dubia, Penn, B. F. iv. t. 44. f. 17. 



There are many other species in the British Museum and other 

 collections which want to be specially studied. 



Fam. III. HuMPHREYIADcE. 



The animal at first free and covered with two shelly valves, which 

 become united into a single plate, which expands on the sides and in 

 front, forming a bag-like cavity, which is attached by its outer 

 surface to shells or rocks, and as the animal increases in size is ex- 

 panded behind into a shelly tube with a circular aperture. The front 

 of the mantle is furnished with scattered tentacles, which are emitted 

 through tubular pores on the upper part of the front of the tube and 

 round the circumference of the part by which it is attached. 



The shells are attached to the surface of shells or rocks, and not 

 sunk into their substance ; nor do the animals live sunk in the sand 

 like Aspergillidce and Gastrochcenidce. 



HUMPHREYIA. 



The character of the family. 



I have named this genus after Mr. George Humphrey, the con- 



