282 Rev. Mr. Berkeley on the 



this is at first thick, but soon becomes attenuated, and enters the base of 

 the penis, after liaving taken a short flexuous course above it. The penis 

 is a flat, Hgulate, transversely wrinkled, pointed process, lying when at 

 rest parallel with the recttun, and folded up in the middle upon itself. 



The ovary is too indistinct to be clearly developed ; from this proceeds 

 the oviduct, which is a flexuous thread, very fine at its origin, but gradu- 

 ally becoming thicker, till it enters into the matrix. The posterior half 

 of this is smooth, and grooved for the reception of the rectum ; the an- 

 terior half deeply phcate on each side externally, and internally furnished 

 with complicated folds, as in Helix. I could find no trace of the organ 

 which Cuvier calls " vessie." 



The most remarkable circumstance in the structure of the animal, and 

 apparently the most anomalous, is the lateral insertion of the oesophagus : 

 whereas the entrance to the stomach is generally at one extremity, and the 

 orifice by which the food passes into the next organ of digestion, at the 

 opposite extremity. 



If, however, we regard the lower portion as the rudiment of an ex- 

 tremely transversely dilated gizzard, we shall approach very nearly to the 

 structure of some Pidmonifera. This may perhaps at first sight appear 

 unwarrantable : but if we imagine the flexuous muscular line to be ad- 

 nate with the lower portion of the sac tlirough its whole length, and per- 

 forated to receive what passes from the oesophagus and biliary duct, we 

 should then have arrived (at no very great distance) at the structure of 

 Onchidium, in which the first stomach is in reality very much transversely 

 dilated. 



In the structure of the seminal secretory organs, it almost exactly re- 

 sembles Planorhis and Limnea, except that the filamentous portion of the 

 testicle is so much longer, approaching, in ^lis latter respect again, the 

 structure of Onchidium. 



The structure of the matrix and heart bear a very close resemblance 

 to that of Helix ; so that with the exception of the free border of the 

 mantle, and the long, armed tongue, in addition to the circumstance of 

 the sexes being separate, there is nothing in its structure which can make 

 us hesitate about its real affinity with other air-breathing Mollmca. 



