218 DE. C. CHILTOX ON THE SUBTEERANEAN 



jointed, though according to their figure theii" " first joint " of the endopodite is quite 

 continuous with the true peduncle and evidently a part of it. 



Gerstaecker considers the branch I have described as the exopodite to be the endopodite 

 dt' inner branch ; and in this he may perhaps be right, though without an appeal to embry- 

 ology there seems to me little to help us to decide which is the exopodite and which the 

 endopodite, and I have therefore followed the majority of authors. In Myssiwa as 

 figured by Stebbing the shorter branch certainly appears to be the endopodite ; but this 

 may be apparent only, and due to the fact that in the figure the animal is " viewed dorso- 

 lateraUy " [106, pi. xxv. fig. v. Fl.'\. 



AMPHIPOBA. 

 Genus Crangontx, Spence Bate. 



(British Sessile-eyed Crustacea, vol. i. p. 326.) 



The following is the definition given by Spence Bate when establishing this genus : — 

 " Superior antenna? having a secondary appendage. First pair of gnathopoda rather 

 larger than the second. Posterior pair of pleopoda unibranched, not longer than the 

 preceding pair. Telson single, entire." 



In his subsequent explanation he gives the additional information that the eyes are 

 imperfectly developed, that the superior antennae are not much longer than the inferior, 

 but rather more robust, and that the first two pairs of legs are small, rather unequal in 

 size, and subchelate. 



Numerous species belonging to this genus have been described by Packard, O. P. Hay, 

 S. I. Smith, Grube, &c., but, so far as I am aware, no one has revised the characters of 

 the genus, although it is evident that this must be done before it can be made to suit all 

 the species that have been assigned to it. The genus Stygobromus, Cope [30], is con- 

 sidered by S. I. Smith [104] to be equivalent to Crangonyx ; but Cope's description is 

 very imperfect, and does not in any way add to our knowledge of the genus. Wrzesni- 

 owski points out that no description of the mouth-parts of Cranyonyx is known to him 

 [124, p. 635]. I am able to give below some account of the mouth-parts of Crangonyx 

 compaotus; and from this it will be seen that in the mouth-parts the genus a^Jjjroaches 

 very closely to Niphargus, which it resembles also in many other points, such as in the 

 antennae, the gnathopoda, and the uropoda. Although Spence Bate described the 

 terminal pair of uropuda as e<«jbrauched, the inner ramus is really present in C. gracilis 

 and 0. compactus, and probably in others, though it is rudimentary as in Nipthargus. 

 It appears, however, that there is a great amount of variation in the development of the 

 terminal uropoda in dilferent species ; this has been pointed out by O. P. Hay, who 

 shows the transition in three species as follows : — 



C. gracilis has the outer ramus of the third uropoda twice as long as the peduncle, 



the inner ramus present, but rudimentary. 

 C. hi/urcus has the outer ramus of the third uropoda two-thirds the length of the 

 peduncle, while it is douljtlul whether there is anything to represent the inner 

 ramus. 



