THE NEMATODE FAMILY GNATHOSTOMID^. 



283 



Specific Diagnosis. 



EcHixocEpnALUs sPiNosissiMus (v. Linst.). 



Head-bulb Avith 30 to 40 rows of hooks, each row contaiiiiiig 

 ■several hundreds. Dorsal and ventral lobes of lips bear two 

 teeth each. 



For list of hosts, see p. 289. 



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

 PL lY. fig. 19 ; PI. Y. 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 Urogjjmnus asperrwms. It is a form 

 intermediate in several features between U. sj^inosissimus and 

 a third species {E. mnltidentatus) 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. sjnnosissimus. 



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

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

 E. sp'mosissimus. The head-bulb (text-fig. 30), however, is much 



Text-figure 31. 



Bchinocephalus soiitluvelli. Caudal ex'tremit}' of female ; ventral view. 



more like that of the next species, E. mnltidentatus, 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. s^yinosissi- 

 mas and E. muUidentatus. 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 oesophagus. In the male, the first 

 pair of caudal papilla3 (PI. Y. tigs. 21, 22), near the tip of the tail. 



For s]3ec'ifiic diagnosis, see p. 285. 



