1922.] 



H. A. Bayljs and R. Daubney : Parasitic Nematodes. 



271 



Ol 771771. 



Fig. 4. — Toxascaris transfuga. Dorsal lip, viewed 

 from exterior. 



d.r., dentigerous ridge; m.l., median lobe of pulp; 

 pi. .paired anterior lobe; p., papilla; t., transverse 

 process of pulp. 



median unpaired lobe, which is a supporting structure for the cuticle of the inner 

 surface of the lip, and appears to end in short rays which spread out beneath the cuticle. 

 The paired anterior lobes originate 

 from the inner side of the main pulp 

 of the lip somewhat behind its ante- 

 rior limit, so that a kind of transverse 

 groove, as described by Railliet and 

 Henry for the type-species, is formed 

 between the main mass and the ante- 

 rior lobes. Marginal dentigerous rid- 

 ges, composed of relatively very large 

 and rather irregular teeth, are pres- 

 ent. 



The cervical alae are well-develop- 

 ed. The oesophagus is simple (with- 

 out ventriculus) and club-shaped, very 

 stout posteriorly (up to 0*95 mm.), and 

 measures 4-5 mm. in length. There 

 are no oesophageal or intestinal divert- 

 icula. 



The caudal end of the male (fig. 5) is curved ventrally, but the extremity is usually 

 recurved towards the dorsal side. The tail itself measures 0'45-o - 5 mm. in length, 

 is bluntly conical, and ends in a short spike which has a small terminal button, and 

 thus resembles a terminal papilla. The postanal papillae correspond in number, 

 though not exactly in position, with those of T. leonina, the genotype. There are 

 (1) a group of four pairs near the tip of the tail, consisting of two very small ventral 

 and two larger, more lateral pairs. Of the latter the more posterior is the most 

 laterally situated, and the more anterior is the largest, of the group ; (2) an isolated, 

 quite lateral pair; (3) a large pair with double terminations, situated at the posterior 

 limit of a kind of raised wall of cuticle which runs forward and round the cloaca, 

 bounding a horseshoe-shaped depression. The edges of this "wall" are usually 

 curved inwards, so that the terminations of the papillae face towards the mid-ventral 

 line ; (4) the first of a series of upwards of thirty pairs of papillae which extend for a 

 considerable distance in front of the cloaca. These papillae are at first close together, 

 and each row tends to resolve itself into two alternating rows, but further forward the 

 row becomes simple and the papillae wider apart. The spicules are very short (about 

 0*65 mm.) and stout, and are tubular structures without alae, and covered with 

 small granulations. 



The tail of the female is short and bluntly conical, almost rounded posteriorly, but 

 with a small papilla-like termination, as in the male. The vulva is situated at about 

 the anterior third of the total length in young females, but in large examples the 

 post- vulvar portion of the body appears to have grown more rapidly than the anterior 

 part, so that the vulva divides the body in the proportion, roughly, of 2 : 5. The 



