112 PYRAMIDELLID.E. 



very curious, and no doubt indicate the seat of a parti- 

 cular function ; probably they are a modification of the 

 organs of smelling. They have not been observed in 

 other genera." The snout (" mentum " or chin, Loven) 

 corresponds in position with the head of a Rissoa, but 

 has a different office. It is like the snout of a pig; 

 useful for finding food, not for eating it. The head of 

 an Odostomia occupies the central space between the 

 tentacles in front ; it consists of a true proboscis, which 

 is protruded only now and then, and appears to be suc- 

 torial. There are no jaws or spiny tongue. Some 

 species of Odostomia, particularly those of the typical 

 kind, inhabit the coasts at low-water mark, lurking 

 beneath loose stones, and at the base of Corallina offici- 

 nalis and small seaweeds in rock-pools ; others are found 

 in the laminarian zone ; a few occur in deep water, 

 beyond the range of vegetable life. In all probability 

 they subsist on polyparia and other animal substances 

 of a soft nature, because the tongue or lingual riband is 

 edentulous. I think M. Petit must have been mistaken 

 in saying (Journ. Conch, viii. p. 250) that they live on 

 seaweeds. Two of our most common species (0. pallida 

 and 0. unidentata) are frequently met with on the 

 " ears " of living Pecten maximus and P. operculums ; 

 and, from their habitual proximity to the excretory pas- 

 sage of the scallop, it may not be unreasonable to infer 

 that they subsist on its faeces. Mr. Norman was of 

 opinion that specimens of 0. pallida, which he dredged 

 in the Firth of Clyde, fed on a red sponge (Halichrondria 

 /armaria, Bowerbank) that occasionally covers P. oper- 

 cularis. I have often taken specimens from the ears or 

 wings of scallops which had no such incrustation. The 

 shell is usually white ; but a few species are banded with 

 reddish-brow T n, or tinged more or less deeply with that 



