OXYUEIDyE. 



is strongly developed, there being, according to Walter, four 

 longitudinal muscles, two dorsal and two ventral, passing from 

 one extremity of the body to the other. These lie immediately 

 beneath the corium, being intimately blended with the latter in the 

 regions of the tail and head. 



In regard to the digestive system, some discrepancies have 

 arisen in the descriptions of authors in consequence of the varying 

 aspect of the worms under different conditions. Thus as regards the 

 mouth, when the retractile papillae are drawn inwards, all that we 

 see is a simple, rounded oral aperture, such as is faithfully repre- 

 sented by Mr. Busk in the accompanying drawing of Oxyuris 

 curvula (Plate lY., lig. 4). At other times, the papillge being tem- 

 porarily exserted, the oral aperture presents a trilobate appearance, 

 very similar to the condition normally characteristic of the genus 

 Ascaris. From the observations of Wiilsteia and Wedl, moreover, 

 it would seem that the papiUse are not invariably three in number, 

 for, in the case of 0. vermicularis and 0. ornata, four such promi- 

 nences may co-exist; whilst in the retracted buccal apparatus 

 here figured, at least six or seven corresponding ridges may be 

 seen, partially concealing eight or nine sharply-pointed dentules 

 or stylets. These tooth-hke structures appear to have been 

 noticed by several observers, and Wedl has described a special 

 dental apparatus in the stomach of Oxyuris vermicularis, which 

 is probably distinctive. The long infandibuhform continuation 

 of the buccal cavity is usually divided into a short pharyngeal 

 portion and a long triangular oesophagus, the latter being sepa- 

 rated from the globular stomach by a very marked constric- 

 tion. This latter organ is succeeded by a second less marked 

 constriction at the upper part of the intestinal canal, which is 

 much expanded, and is by some regarded as part of the stomach 

 itself. After this the ahmentary canal gradually narrows into the 

 intestine properly so called, and terminates by a wide anal cleft, 

 which in the male also serves to give exit to the intromittent 

 spiculum. 



