THE NEMATODE FAMILY GNATHOSTOMIDiE, 283 



Specific Diagnosis. 



ECHIXOCEPHALUS SPINOSISSIMUS (v. Liust.). 



Head-bulb with 30 to 40 rows of hooks, each row containing 

 several hundreds. Dorsal and ventral lobes of lips bear two 

 teeth each. 



For list of hosts, see p. 289. 



3. EcHiisrocEPHALUs souTHWELLi*, sp. n. (Text-figs. 30-32; 

 PI. IV. fig. 19 ; PI. V. figs. 20-23.) 



This species, which we name in honour of Mr. Southwell, to 

 whose kindness we are indebted for this and much of our other 

 material, was also found in Urogymnus asperrimus. It is a form, 

 intermediate in several features between E. spinosissimtos and 

 a third species {U. multldentatus) to be described below, and all 

 these three species were found together in the same individual 

 host. 



The present species is rather shorter and considerably more 

 slender than E. spinosissimus. 



The lips (PI. lY. fig. 19; PI. V. fig. 20) are rather squat, 

 and their dorsal and ventral lobes bear only two teeth each, as in 

 E. spinosissimus. The head-bulb (text-fig. 30), however, is much 



Text-figure 31. 



JSchinocephalus southivelli. Caudal extremitj' of female; ventral view. 



more like that of the next species, E. multldentatus, though 

 smaller and less flattened antero-posteriorly. There are from 15 

 to 18 rows of hooks, which have a maximum length of 0"035 mm., 

 and are thus intermediate in size between those of E. sjnnosissi- 

 mus and E. multidentatus. The number of hooks in each row is 

 also intermediate, there being, as nearly as can be estimated, from 

 150 to 200. 



The cuticular striation on the body is rather coarse. The cervical 

 sacs are nearly as long as the cesophagus. In the male, the first 

 pair of caudal papillae (PI. Y. figs. 21, 22), near the tip of the tail, 



* For spe3ific diagnosis, sse p. 285. 



