CEUSTACEA OF NEW ZEALAND. 179 



the origin of the cave-fauaa " [83, p. 35] . This species docs not possess even rudimentary eyes, but in 

 C. Packardii an imperfect eye is present. The latter species is very close to C. gracUis, Smith, and the 

 " differences are all such as very naturally lead to the supposition that this subterranean form has been 

 derived from the C. gracilis at no very remote period" [83, p. 36]. 



The brain of the eyeless CcecidotcEa is described and compared with that of AseUus, from which it appears 

 " that the eyeless C<ecidot(Ea differs from Aaellus, as regards its brain and organs of sight, in the complete 

 loss of the optic ganglion, the optic nerve, and the almost and sometimes quite total loss of the pigment- 

 cells and lenses" [83, p. 109]. Ccecidotiea does not appear to be always totally eyeless. In specimens 

 from a well at Normal, Illinois, the eye was represented by a black speck, varying in distinctness ; 

 no trace of eyes could, however, be detected in most of the Mammoth Cave specimens. The brains of 

 eyed and eyeless species of Crangonyx were also examined and compared, and the result thus stated : 

 " we see very slight diflferences between the brains of the eyed and the eyeless Crangonyx. The optic 

 ganglia have about the same proportions as do the other lobes and the arrangement of the ganglion-cells. 

 Perhaps striking differences should not be expected, as the eyes of the eyed species of Crangonyx 

 are small compared with those of Gammarus." 



Numerous references to these cave Crustacea are made in the course of the author's remarks on the 

 general question of the peculiarities of the cave-fauna. 



Thos. R. R. Stebbing [108] in his " Report on the ' Challenger ' Amphipoda," published in 1888 

 notices in his biographical introduction previous writings on the blind Amjjhipoda found in caves, wells 

 and the deep waters of lakes, with occasional remarks and criticisms of his own, most of which have 

 been already incorporated above. 



R. MoNiEZ [78], in 1889, gave a full account of the fauna of the " Departement du Nord," and 

 particularly of the town of Lille, and besides giving the Crustacea found in this locality he mentions also 

 those recorded from other places by previous observers. He describes under the name Gammarus 

 fluviatUis, var. d'Emmerin, a single specimen from the reservoirs of Emmerin, which seems to differ from 

 the Gainmari found at the surface in much the same way as the G. judex, var. subterraneus, described by 

 Schneider does ; but as the last segments of the pleon bear groups of strong spines, it approaches more 

 nearly to G. fluviatUis. Moniez says that it forms in some maimer a couiiectiug-link between the 

 surface type and the variety described by Schneider. The number of joints in the flagella of the 

 antennae are rather numerous, the secondary appendage of the upper antenna containing five joints, 

 a point to which Moniez attaches some importance. The importance of this is, however, somewhat 

 lessened when we remember that the single specimen examined was of large size, viz. 22 millim. in 

 length, for the numbers of joints in the flagella of the antenuEe, and also in the secondary appendao-e 

 appear to increase with the size of the animal ; thus I have a large specimen of Gammarus frugihs, 

 14 millim. long, which has the secondary appendage composed of nine joints, whilst iu another only 

 7 millim. long there are only six joints, and 1 have seen specimens with even fewer joints than this. Of 

 course, in species where the normal number of joints is very small, the variation will not be so great, but 

 the same reasoning will apply to a modified degree. 



Moniez does not accept the genus Niphargus, and under the name Gammarus puteanus, Koch, he 

 describes two forms ; the first, " G. puteanus a main triangulaire," corresponds to Xiphargus uquile.r, 

 Spence Bate, and to A', puteanus, var. onesiensis, Humbert, and this is the species which should he 

 considers, be looked upon as the true type of AlpJiargus puteanus. The other form, " Gammarus 

 puteanus k main ovale," differs iu the form of the hand of the guathopods, and partieularlv in the last 

 uropoda, which are short and bear only one branch consisting of a siugle joiut, thus resembliuo- 

 Crangonyx, though the telson is double and not simple as in that genus. This form Moniez constantly 

 found associated with Niphargus puteanus (a main triangulaire), but in much fewer numbers; and as 

 he cannot identify it with any of the previously described species aud is not inclined to see a new 

 species in it, he suggests that it may be a second form of the male of Niphargus puteanus. 



SECOXD SERIES. — ZOOLOGY, VOL. VI. 2i 



