OXYUMS VERMICULARIS. 367 



cavity of the oesophagus. Externally there are three strong 

 muscles, which determine the prismatic form ; and inwards from 

 these angles the skin is seen to be furnished with broad folds, 

 covered in the earliest periods with distinct, delicate epithelium, 

 which afterwards becomes firmer. All this is surrounded by a 

 firm, structureless envelope, a continuation of the epidermis, 

 which afterwards becomes the peritoneum. 



After the oesophagus and behind the constriction follows the 

 strongly muscular stomach, with a peculiar dental apparatus, 

 according to Walter. The cavity of the stomach is also prismatic 

 at first, but dilates immediately after a second constriction. The 

 folds are wanting here, but instead of them three converging 

 cones are seen which are firm, acute, and chitinous, originating 

 in the walls of the cavity, and are furnished with points pro- 

 jecting freely into the cavity. Superficially they are covered 

 with small diverging folds, and in consequence have an undulated 

 appearance. According to Walter, an epithelium is only ob- 

 served in the Oxyurides in their earliest youth. On the outer 

 surface of the walls of the stomach there are radiating muscular 

 fasciculi issuing from a second membrane which exists between 

 the stomach and peritoneum. On these circular muscles, 

 between the above-mentioned membrane and the peritoneum, 

 there follows a new strong muscular layer. Immediately behind 

 the stomach there is another constriction, with which the intes- 

 tine commences ; the course of the latter is somewhat different 

 in the two sexes. After the constriction, which is followed by 

 the corresponding dilatation, the intestine makes a turn forward, 

 and afterwards runs, always maintaining a nearly equal diameter, 

 in a pretty straight line, and only making a few convolutions, in 

 the female more in the middle of the worm, but then passes to 

 the inner side and opens into the somewhat narrowed anus, about 

 1-798 mill. = 0-797'" P. = 0-819'" V. from the apex of the tail 

 on the inside of the worm, and indeed in its lateral margin. In 

 the male the circumstances first mentioned also take place, only 

 here the intestine always runs on the outer side of the worm into 

 the caudal extremity, where it opens on the outer side of the 

 penis, by a cleft-like orifice, or perhaps by a common orifice for 

 the penis and anus. Wedl has erroneously regarded the seminal 

 chord as the intestine. 



The anatomical structure of the intestinal canal is as follows : 

 The peritoneum of the stomach is continued into the peritoneum 



