220 DE. C. CHILTON ON THE SUBTERRANEAN 



C. compactus in the possession of smr^Ze-branched pleopoda, or whether they have normal 

 pleopoda with two branches *. Unfortunately, the pleopoda are usually neglected in the 

 brief descriptions given of new species, and are seldom referred to even in more elaborate 

 descrijitions ; this is, of course, due to the fact that the pleopoda are less subject to 

 variation than most organs of the Amphipoda. To such a degree is this the case that 

 Fritz Miiller speaks of them as being " reproduced in wearisome uniformity throughout 

 the entire order " [79, p. 15, footnote]. Stebbing [108, p. 350] has, however, pointed 

 out that this statement is somewhat overdrawn, and has perhaps had the disadvantageous 

 tendency of discouraging the examination of these organs. 



Wrzesniowski [12i, p. 63i] remarks that there is much variation in the degi-ee of 

 development of the eyes in the different species of Cranyonyx, some being described 

 as without eyes, others having more or less perfectly developed eyes. I had originally 

 stated that I could find no eyes in Crangonyx compactus ; I find, however, that they are 

 represented by two or three small lenses, which, however, do not appear to be furnished 

 with any pigment, and are probably useless so far as sight is concerned. 



As I have examined only the one species belonging to the genus, and as the 

 descriptions of other species to wliich I have access do not give much information on 

 the details of then* structure, I have not attempted to revise the characters of the genus, 

 but must leave that for some one with a wider knowledge of the subject. It will be 

 sufficient for the present to repeat that the genus appears to differ from Niphargus in the 

 more robust body, in the last pair of uropoda, and in the single uncleft telson. 



Crangonyx compactus, Chilton. (PI. XX. figs. 1-30.) 



Crangonyx comj^aclus, Chilton, New Zealand Journal of Science, vol. i. (March 1882) p. 44; id. 

 Transactions New Zealand Institute, vol. xiv. p. 177, plate s. figs. 13 to 19; Thomson & Chilton, 

 Transactions New Zealand Institute, vol. xviii. p. 147; INIoniez, "Fauna des Eaux souterraines du 

 Departement du Nord &c.," extrait de la Revue Biologique du Nord de la France, tome i. (1888- 

 1889) p. 50 ; Wrzesniowski, ' trzech kielzach podziemnych,' De tribus Crnstaceis Amphipodis subter- 

 raneis, pp. 16, 41, 90 ; Wrzesniowski, " Ueber drei unterirdische Gammariden," Zeitschrift fiir wisseu- 

 schaftliche Zoologie, L. 4, pp. 611, 634, 698. 



Specific diagnosis. Eyes small, without pigment, consisting of two or three imperfect 

 lenses only. Upper antennae about one-third the length of the body ; first joint of 

 peduncle much larger than the second; flagellum longer than the peduncle ; secondary 

 appendage small and slender, consisting of one long and one short joint. Peduncle 

 of lower antennge longer than peduncle of upper; flagellum shorter than the last joint 

 of peduncle, consisting of four joints. Gnathopoda subequal, propodos of each only 

 slightly broader than the carpus ; palm about one-half the length of the inferior edge, 

 defined by a stout spine on each side. Perseopoda subequal, the last three pairs having 

 tlie basi narrow, not expanded as usual. Inferior edge of the three anterior segments of 

 the pleon furnished with five or six small seta?. The three pairs of pleopoda one- 

 branched. The uropoda short and broad, the third pair with the outer branch about 



* In both C. gracilis. Smith, and C. mucronatus, Forbes, specimens of which have recently been sent to me by 

 Mr. W. P. Hay, the pleopoda have the normal two branches. 



