SPECIAL ANATOMY. £01 



between it and the extremity of the pedal disc. The 

 anal aperture opens at the posterior margin of the latter 

 orifice. The generative apparatus has two distinct ex- 

 ternal apertures, distant from each other. The male 

 genital orifice is placed just beneath the mouth, between 

 it and the blind sac, mchning to the right. The female 

 orifice is situated upon the inferior part of the left side 

 of the mantle, midway between the head and tail. 



As usual, the body has two catties, of which the pul- 

 monary occupies a position at the right posterior part, 

 beneath the mantle, and extending backwards on the 

 right to the tail. 



Chapter ii. — general remarks on the terrestrial 

 testaceous gasteropoda. 



A testaceous gasteropod resembles a slug with the 

 greater portion of the viscera squeezed out upon the 

 back, and arranged in a turbinate manner. The turbin- 

 ate mass is always an exact mould of the testaceous cover- 

 ing of the anunal; its length in the spiral direction holds 

 no proportion with that of the foot, or that part of the 

 body which the animal protrudes from the shell, and dif- 

 fers very much, not only in different genera, but also in 

 different species of the same genus. With an increase 

 ni length a proportionate decrease in breadth is observa- 

 ble, and vice versa. In Pupa it reaches its maximum 

 length and narrowness ; in Succlnea it has the mini- 

 mum length, and the greatest proportionate breadth. 



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