1922.] 



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



267 



also mentions differences in the relative lengths of parts of the female reproductive organs, but such 

 differences ma} 7 constantly be observed in female nematodes of different ages, of the same species and 

 from the same host. In our opinion, the evidences of identity furnished hy the structural characters 

 mentioned are of much greater weight. 



Recent experimental work by Stewart and others has shown that A. lumbricoides can reach a 

 certain stage of development in the rat, mouse, guinea-pig and rabbit, but it has not yet been found to 

 settle in the intestine and attain sexual maturity in these animals. The present record of the adult 

 worm in squirrels (assuming, as we believe to be justifiable, that the species is the same), shows that 

 the development may, under suitable conditions, be completed in a rodent. 



Ascaris vitulorum, Goeze, 1782. 

 (Figs. 1—3.) 



The distinctive characters of this form do not seem to be at all well known, and 

 we are not aware of any recent description of it.' Ransom (1911) gives only the 

 briefest details of its anatomy, and these seem to have been mainly quoted from Neu- 

 mann. A few specimens taken from a calf at Siripur, Bihar, though in rather poor 

 condition, enable us to add a few details to the description, and to correct others. 



Our specimens measure from 85 mm. (male) up to 140 mm. (female) in length. 

 The cuticle is marked with transverse rings at intervals of 003-0075 mm. Finer 

 striations, if present, were not seen. 

 The diameter of the head, at the base 

 of the lips, is about 05 mm.; that of the 

 neck, immediately behind the lips, 07 

 mm. The lips (fig. 1) are broad at the 

 base and narrow in front. The dorsal lip 

 carries a pair of large, simple papillae ; 

 each ventro-lateral lip a large, lozenge- 

 shaped papilla towards the ventral side 

 and a small, round papilla laterally and 

 more anteriorly. The pulp of each lip 

 sends out two rounded lobes anteriorly, 

 and from the inner surface of each lobe 

 a blunt, inwardly- directed process origi- 

 nates. The two processes converge 

 slightly towards the middle line of the lip. 

 Dentigerous ridges, with coarse teeth, 



are present. There are no interlabia. The oesophagus is modified posteriorly into 

 a small, almost globular " ventriculus," or glandular bulb (fig. 2), measuring 

 about 035 mm. long and 0*45 mm. wide. This is not distinctly constricted off from 

 the muscular portion of the oesophagus, but is preceded by a slight narrowing of the 

 latter. The entire oesophagus measures about 4 mm. in length. The nerve-ring 

 surrounds it at about o - 8 mm. from the anterior extremity. 



1 Since this paper was prepared, a description has been published by Boulenger (Parasitology XIV, 1, 1922, p. 87), 

 which agrees on the whole with ours, except that he appears to have seen more pairs of postanal papillae than we could 

 detect in our material. 



o-inun. 



Fig. 1. — Ascaris vitulorum. Dorsal lip, viewed 

 from exterior. 



a., anterior lobe of pulp ; d.r., dentigerous ridge ; 

 i. } internal process of anterior lobe ; p., papilla. 



