ACANTHOCEPHALA 559 



The worms are about 2-5-3-5 mm. in length and o-4-o-7 mm. in maximum thickness. 

 The proboscis is 0-6 mm. long in the male, and 0-7 mm. in the female. Its maximum 

 diameter, in the male, is o- 18 mm., in the female 0-22 mm. It bears 14 longitudinal rows of 

 hooks, each containing 12-14. The largest of the hooks on the ventral side are 0-0875 mm. 

 in length (in a straight line from tip to insertion), while those on the dorsal side measure 

 not more than 0-065 mrn- The spines on the anterior region of the body are arranged 

 in irregular transverse rows, which extend right round on to the dorsal surface, though 

 here the spines become very minute. The largest of the body-spines, on the ventral 

 surface, are about 0-03 mm. in length. In fully-extended specimens the spines extend 

 back ventrally beyond the level of the middle of the proboscis-sac. This organ is about 

 0-7 mm. long in the male and 0-9 mm. in the female. The lemnisci are as long as, or a 

 little longer than, the proboscis-sac. The eggs measure about 0-05 mm. x 0-015 tiiti- 



This species is clearly very closely related to the last described, and differs in the same 

 respects from previously-known forms. 



Rhadinorhynchus sp. 



Two immature specimens of a species of Rhadinorhynchus occurred in the intestine 

 of Naucrates diictor off the Canary Islands, October 16, 1925. In both the proboscis 

 is retracted. 



REFERENCES 



Baylis, H. a., 1923 a. Report on a Collection of Parasitic Nematodes, mainly from Egypt. Part I. 

 Ascaridae and Heterakidae . Parasitol. xv, 1-13. 



1923 b. Some Nematodes of the Genus Cucullanus /row Fishes of the Nile. Ann. Mag. Nat. Hist. 



(9). xn, 233-6. 

 Baylis, H. A. and Daubney, R., 1926. A Synopsis of the Families and Genera of Nematoda. London, 



British Museum (Nat. Hist.). 

 Gendre, E., 1927. Nematodes parasites des Poissons de la Cote de Mauritanie. Bull. Comite d'litudes 



Hist, et Sci. de I'Afrique Occid. frangaise, x, 2, 258-72. 

 MonN, R., 1858. Prospectus helminthum, quae in prodromo. . .continentur. Sitz. k. Akad. Wiss. Wien, 



XXX, 127-58. 



1861. Prodromus Faunae helmiiithologicae Venetae, etc. Denkschr. k. Akad. Wiss. Wien, xix, 



189-338, Pis. I-XV. 

 Orley, L., 1885 a. A Czdpdknak ds Rdjdknak Belfergei. Termes. Fuz., Budapest, ix, 97-126, Pis. IX, X. 



1885 b. Die Entozoen der Haien und Rochen. Ibid. 216-20. 



