1922.] 



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



283 



o-l mm. 



Fig. 17. — Contracaecum incur vum. Head of male ; 

 dorsal view. 



a, cervical ala ; g., groove in cuticle ; i., interla- 

 bium ; p., papilla. 



show them to belong to the genus Contracaecum. The head corresponds fairly well 



with the figures given by Schneider ((1866), pi. II, figs, n a and b) and by Linton 



((1901), pi. IV, figs. 29, 30), while the 



presence of a long intestinal caecum has 



been noted by Du jardin (1845) and by 



Linton (I. c), although the oesophageal 



appendix was not observed, and Dujar- 



din placed the species among the forms 



now considered to belong to the genus 



Porrocaecum. 



The characters of the caudal end in 

 the male do not appear to have been 

 accurately described. Stossich ((1902), 

 pi. Ill, fig. 1) shows only two pairs 

 of postanal papillae, and a peculiarly 

 shaped tail. Linton's figure ((1901), pi. 

 IV, fig. 32) is scarcely adequate for deter- 

 mination. For these reasons it may be 

 worth while to give some details and figures of the anatomy of the present specimens. 



The larger of the two specimens measures 343 mm. in length and 0*55 mm. 

 in thickness. The diameter of the head is about 0*19 mm. The distance from 

 the head end to the posterior end of the oesophagus (including the small spherical 

 ventriculus) is about 3 mm. The ventriculus is o - i6 mm. in diameter. The oeso- 

 phageal appendix is relatively very long (3 mm.), and the intestinal caecum runs 

 forward to a point T/05 mm. from the head end. The cervical alae originate just 

 dorsally to the lateral interlabia, and extend back to a point about 2 mm. from the 

 anterior end. They are about 0*05 mm. wide at the widest part. The body is rela- 

 tively slender and of almost uniform thickness throughout. The cuticular striations 

 are coarse (up to 0*0125 nim. apart), and form small saw-teeth in optical section. 

 The lips have sinuous margins anteriorly and laterally, and are produced into broad 

 cuticular flanges at the posterior corners. There are deep grooves running round the 

 bases of the lips from the interlabia, similar to those characteristic of the genus 

 Ophidascaris. The interlabia are rather short and compressed between the lips. 

 The ventro-lateral lips are somewhat asymmetrical in shape, though hardly so much 

 so as is indicated by Schneider's figure ((1866), pi. II, fig. 11 b), the ventral angles 

 being considerably produced. The dorsal lip bears a pair of rather small, rounded 

 papillae ; the ventro-lateral lips one each, towards the ventral side. There is a pair 

 of conspicuous, but sessile, cervical papillae situated dorsally to the cervical alae and at 

 o'65 mm. from the anterior end. The nerve-ring is at 055 mm., and the excretory 

 pore at o*68 mm., from the anterior end. 



The tail of the male (fig. 18) is 0*2 mm. long, sharply tapering, curved ventrally 

 and drawn out at the tip into a slender spike. There are no caudal alae. The ven- 

 tral surface of the caudal region, from about 07 mm. in front of the cloaca forward 



