OXYURIS VEKMICULARIS. 363 



oral extremity and on the tail, the epidermis and corium are 

 firmly united, and both turn inwards at the natural openings. 



During the motion of the animal broad folds are formed in 

 the corium, which at the same time compel the epidermis to 

 fold, as may be best detected when old, mature animals are cut 

 through before the anus and behind the pharynx, and the contents 

 of this part of the body are pressed out under the microscope. On 

 the corium we see four seams running through the whole length 

 of the animal (one on each side, and one along the dorsal and 

 ventral surfaces) and between them a fibrous layer. In Oxyuris 

 ornata, the latter sometimes consists of two layers, one transverse 

 and the other spiral, but in general we only see parallel fibres, 

 crossing each other at acute angles. 



In Oxyuris vermicularis, the skin of which is colourless, the 

 transverse striae which are especially distinct during the contrac- 

 tions, are at the above-mentioned distance apart, and the skin 

 projects on the lateral margins in a serrated form. These serra- 

 tions form a double series on each side, the outer of which is 

 more rounded and blunt, the inner more acute and sharper, 

 especially in the males. 



The parenchyma of the body does not extend into the tail, 

 and in the anterior extremity in the neighbourhood of the mouth 

 the lateral surfaces are free from parenchyma, so that when the 

 worm is pressed flat, we see in that part two transversely ribbed, 

 wing-like appendages, which are obtusely rounded off in front, 

 but taper away gradually behind, and become amalgamated with 

 the epidermis of the middle part of the body. They are indi- 

 cated by authors as two lateral, wing-like appendages, composed 

 of broad, band-like, hyaline lobes. The transverse ribs in these 

 appendages, correspond either with the spots, when an intimate 

 contact of the two inner surfaces of the epidermis forming the 

 appendages takes place (either a constant contact, or only a tem- 

 porary one in consequence of the transverse wrinkling occurring 

 during movement), or with transverse nervous branchlets, which 

 I could not ascertain clearly. 



The muscular system of Oxyuris, according to Walter, is 

 very highly developed. Thus, in Oxyuris ornata, close beneath 

 the corium, we find several (4) longitudinal muscles regulating the 

 general movement, and then smaller muscular groups in the 

 interior of the body on various organs, and extremely seldom 

 (only in the male sexual apparatus) muscular fibres running 



