axinus. 247 



of the London Clay as the type. This exhibits all the 

 essential generic characters, except in respect of the 

 hinge, which is not visible in consequence of the matrix 

 in which the shell is imbedded being too hard and com- 

 pact to be removed. It is remarkable, however, that 

 Sowerby added to his description of Axinus, " I suspect 

 it has no teeth." 



Several names for this genus have been attributed to 

 Leach, viz. Thyasira, Thiatira, Thiatisa, and Bequania. 

 The first only is classically correct. Turton called it 

 Cryptodon, Philippi Pty china, and I gave another generic 

 name (Clausina) to one of the species. All these are 

 mere synonyms and superfluous. 



I would recommend those of my readers who are 

 acquainted with the Danish language to read a very 

 interesting account by Professor Sars of the animal of 

 A. Sarsii, contained in his Report of a zoological ex- 

 cursion to the LofFoden Isles and Finmark in 1849. 

 He observes that Axinus differs from all other Con- 

 chifera in the position of its generative organs, which 

 lie outside the stomach, and not within it ; and he com- 

 pares this genus to the Brachiopoda in that respect. 

 He found by a microscopical examination that some 

 individuals were male and others female. 



1. Axinus flexuo'sus*, Montagu. 



Tellina flextwsa, Mont. Test. Brit. p. 72. Lucina flexuosa, F. & H. ii. p. 54, 

 pi. xxxv. f. 4. 



Body clear white : mantle somewhat contracted on the pos- 

 terior side, so as to form a round hole : gills thick, of a red- 

 brown colour : foot placed in the middle of the ventral area. 



Shell roundish-oval, tumid, thin, usually opaque but some- 

 times more or less transparent, scarcely glossy : sculpture, irre- 



* Flexuous. 



