THE NEMATODE FAMILY GNATHOSTOMID^. 



285- 



are quite lateral; the 2nfl, 5th, 6tb, Ttli, and Stli form a loiigi- 

 tudinal series, while the Srd and 4th are a little nearer to the 

 mid-ventral line. Pairs 2-5 form a group rather close together, 

 of which 2 and 4 are small papillae and 8 and 5 relatively large. 

 The intervals between 5 and 6 and between 6 and 7 are abont 

 equal, and greater than those between the posterior pairs, while a 

 much longer interval separates 7 and 8. 



The spicules (PI. Y. figs. 22, 23) are rather slender. A little 

 before the tip each spicule is narrowed and then expanded some- 

 what, before terminating in a conical point. 



In the female the tail (text-fig. 31) is very short. The vagina 

 (text-fig. 32) leads into a very wide uterine sac. 



Specific Diagnosis. 



EcHiNOCEPHALUS souTiiwELLi Baylis and Lane. 



Head-bulb with 15 to 18 rows of hooks, each row containing 

 about 150 to 200. Dorsal and ventral lobes of lips bear two 

 teeth each. 



For list of hosts, see p. 289. 



4. EcHTNOCEPHALUs MULTiDEN'j'ATUS ^, sp. u. (Text-figs. 33-36 ; 

 PI. VI. figs. 24-27 ; PI. VII. fig. 28.) 



This is the third species obtained from the sting-ray, Uro- 

 gymnus asperrwius. In general naked-eye appearance it closely 

 resembles U. southwelli, but is rather shorter and proportionately 

 stouter. The head-bulb (text-fig. 33) is very conspicuous, and 

 gives the worm much the appeai-aiice of a small nail. 



The lips (PI. VI. figs. 24, 25) are well-developed, but not 

 prominent. In structure they are moie complex than in any of 

 the other forms studied by us. The outer portion bears the usual 

 three papillae, and the inner portion is, as usual, trilobed. The 

 cuticle of the opposed inner surfaces of the dorsal and ventral 

 lobes is raised into a number (from 8 to 11 on one lobe) of tooth- 

 like ridges. These teeth are not constant in number or arrange- 

 ment, and are not always symmetiical on the two lobes of the 

 same lip, as may be seen in PI. VI. fig. 25. Whether the teeth 

 of the two lips can be interlocked is uncertain, though their 

 appearance suggests that this is probabl}^ the case. 



The head-bulb (text-fig. 33) is very wide compared with the 

 neck which follows it, and is somewhat flattened antero-posteriorly . 

 There are from 11 to 13 rows of large hooks (text-fig. 34). Each 

 row may be estimated to contain some 100. 



The cervical sacs are, as in E. southivelli, of approximately the 

 same length as the oesophagus, both terminating at a point a 

 little more or less than 2 mm. from the anterior extremitv. 



* For specific diagnosis, see p. 289. 



