Anatomy of Cyclostoma elegcms. 281 



sac nearly half way, and then curves over, on the upper surface, to the 

 opposite side, vjrhere it meets a short, raised, pale, cartilaginous edge, si- 

 tuated on the under surface of the sac ; thus forming, when closed, a dis- 

 tinct pouch, into which the food enters, (with the bile by means of the 

 biliary duct immediately beneath the orifice of the oesophagus,) and is pre- 

 vented from returning in the direction in which it entered, by means of 

 the muscular rib ; the cartilage acting as a valve to regulate its progress 

 into the next portion of the sac. On each side of the rib, are a few lon- 

 gitudinal narrow folds, especially on that side nearest the entmnce of the 

 oesophagus, towards which they diverge slightly; perpendicular to these 

 on each side, transverse streaks are discernible. Above this, correspond- 

 ing to the two apparent constrictions above noticed, are two small cavi- 

 ties, which are likewise furnished with folds, the upper one, however, 

 more conspicuously so, one edge of which is muscular, being indeed a 

 continuation of the rib ; and from the upper of these proceeds a muscu- 

 lar line, parallel with the margin of the sac, and a similar one in the 

 under side of the sac, which at its origin just above the orifice of the 

 oesophagus, and close to th(3 upper cavity, is furnished with a small obtuse 

 cartilaginous projection. 



The intestine, as soon as it is given off from the top of the sac, takes 

 a bend beneath it, and again almost immediately resumes its former di- 

 rection, and then, after running parallel with the sac through its upper half, 

 takes another turn, running in the female along a groove in the matrix, 

 and above the vas deferens in the male. 



The fseces are elliptic. The intestine is nearly enveloped in a white 

 granulated mass, composed of very unequal globular granules ; which is 

 perhaps an omentum. The liver envelopes the under side of the stomach, 

 and from thence runs to the top of the spire, of a yellowish brown, con- 

 sisting of minute obtuse lobes, dotted with black. It is not easy to de- 

 velope it in so small an animal. 



Until the liver passes under the stomach, the testicle is confluent with 

 it, exactly following the form of the shell, but at that point it gives off a 

 very fine thread, which gradually thickens, and passes many times from 

 right to left, and from left to right, it then becomes gradually attenuated, 

 till it passes laterally into a subglobose mass, which is composed inwardly 

 of parallel thin plates, and again gives off laterally the vas deferens ; 



