KOLLIKER, ON VEGETABLE PARASITES. 181 



in dentine, they have some relation to the nutrition of the 

 shells. In my work upon cuticular formations and pore- 

 canals, I remarked with respect to this subject, that certain 

 of the tubuli described by Carpenter very closely resembled 

 the pore-canaliculi of cuticular structures, among which 

 I placed the bivalve shells ; but at the same time, I stated 

 that the horizontally spread and anastomosing canals 

 of other genera must be differently explained. Lastly, the 

 latest author who has occupied himself expressly with this 

 subject, Wedl, has described the tubuli in all bivalves as 

 vegetable parasites, with which opinion I now entirely coin- 

 cide. 



The genera and species examined by me are the following: 



(a) Anemia ephippium. 



To Dr. Carpenter's description I have chiefly only this to 

 add, that in most of the coarser fungus-filaments rounded 

 sporangia, and, as it appears to me, principally terminal, 

 are placed. To judge from two of Dr. Carpenter's prepara- 

 tions, the fungus-filaments in the most superficial layers 

 of the shell constitute a close network, from which straighter 

 and less branched filaments, of greater or less size, run in very 

 oblique directions into the inner layers. The sporangia are 

 situated principally in the neighbourhood of the mycelium- 

 plexus above mentioned, and measure as much as O02"' or 

 more. 



(b) Cleidotharus cliamoides 



Contains, throughout the entire thickness of the shell, 

 numerous fungus-filaments, usually of no inconsiderable size 

 (O'OOS"' or even 0'005"'), which in certain layers are much 

 branched, and in the outermost coloured lamina present 

 elongated enlargements, which can scarcely be regarded as 

 anything but sporangia. 



(c) Lima scabra. 



A horizontal section, procured from Dr. Carpenter, afforded 

 no distinct evidence with respect to the distribution of the 

 fungus. The filaments, having an average size of OOOl"' and 

 , 002'",ran for the most part horizontally, some much branched 

 and, as it appeared, also anastomosing, some straighter and 

 supporting terminal sporangia, and in certain spots enlarge- 

 ments probably of the same nature. 



(d) Area No<e. 

 A section of this shell, procured in England, presented only 



