514 C. CLIFFORD DOBELL. 



food. Horuell/ from his own observations on tlie style of the 

 oyster, i-egards the style as a food-catching apparatus, as was 

 maintained earlier by Barrois. Pelseneer - states that " the 

 product of its solution forms a sort of cement which encrusts 

 any hard substances that may have been ingested and thus 

 protects the delicate walls of the intestine from injury.'^ 



This is not the place to discuss these and other views which 

 have been put forward regarding the functions of the crystalline 

 style. But as this is of some importance in connection with 

 the organisms which inhabit it, the structure itself cannot be 

 ignored. It appears to me most probable — from the observa- 

 tions recorded by others — that the crystalline style serves 

 both to catch food particles and prepare them mechanicalh^ 

 for digestion and also to assist in the digestion of the amyloid 

 constituents of these particles. 



In some Lamellibranchs — e. g. in Pecten (Gross, 1910) — 

 the Cristispirte are found in the stomach and intestine, and 

 only rarely in the crystalline style. It therefore seems to me 

 probable that Cristispira is really a gut parasite, which 

 often happens to find the substance of the crystalline style a 

 suitable culture medium. The same is also suggested by the 

 occurrence of Bacteria in the style. The latter contains some 

 12 per cent, of globulin, with about 1 per cent, of salts and 

 88 per cent, water. '^ It might therefore well serve as a 

 culture medium for many micro-organisms which reach it 

 accidentally. I do not think any deeper significance need 

 be attached to the association of Protista with the crystalline 

 style. 



CeISTISTIRA veneris, N. SI'. 



I will now record my observations upon the structure 



' Hornell. *" RejDort on the Operations on the Pearl Banks during the 

 Fishery of 1905;" ' Ceylon Marine Biological Reports." Part II, June. 

 1906. 



^ Pelseneer, " Mollusea," in Lankester's ' Treatise on Zoology,' 

 London, 1906. 



3 Mitra.loc. cit. 



