448 W. N. F. WOODLAND 



'2 mm. The general shape of these parasites is indicated in 

 PL 25, fig. 24, which in itself provides evidence that the body is 

 very contractile and therefore variable in form and length. 

 In the general topography (PL 25, fig. 25) of the genitalia (and 

 in the structural details described below) these parasites are 

 closely related to C . 1 a t i c e p s and other previously described 

 species of Caryophyllaeus, since, as in these species, the 

 genital openings are situated very near to the posterior end 

 and the uterus is therefore relatively very short, and the 

 testes extend over a great length of the body. One feature, 

 however, in which C. filiformis markedly differs from 

 C. laticeps and all other species of Caryophyllaeus 

 is the total absence of vitellaria posterior to the ovary, and of 

 a post-ovarian region, the ovary in most cases extending 

 to the extreme end of the body. 



In all specimens of C . filiformis the genital apertures are 

 situated well within the last one-seventh of the body-length 

 (from one-twelfth to one-seventh according to the length of the 

 head). In six typical examples the lengths of the three regions 

 were as follows : in a specimen measuring 21 mm. long, the 

 head measured 10 mm. and the testicular region 9 mm. ; in 

 a specimen 23-5 mm. long, the head was 11-5 mm. and the 

 testicular region 10 mm. ; in a specimen measuring 21-5 mm. 

 the head was 9 mm. and the testicular region 10-5 mm. ; in 

 a specimen measuring 20 mm. the head was 8 mm. and the 

 testicular region 10 mm. ; in a specimen measuring 11-5 mm. 

 the head was 5-5 mm. and the testicular region 5 mm. ; and in 

 a specimen measuring 15-3 mm. the head was 5-5 mm. and the 

 testicular region 8-3 mm. In five of the specimens (PL 25, 

 figs. 26, c, d) the testes extended much more anteriorly, almost 

 to the extreme front of the head — thus in a specimen measuring 

 22 mm. the head was only 1-5 mm. long, while the testicular 

 region was 1 9 mm. — but this is not the normal condition, and 

 intermediate conditions exist between this and the normal. 



The head, as already stated, is extremely contractile and 

 assumes the most various shapes (PL 25, fig. 26, a, h, c, d, e). 

 When uncontracted it is fairly flat and ribbon-shaped (PL 25, 



