Annals of the Transvaal Museum. 
99 
than of I and II. All with normal setae. Terminal joint not elongated in 
the first two pairs. 
Pleopods : normal ; bear coupling hooks on basal portion ; the longest 
pleopod is the second. 
Uropods : the first is the longest; the third uropod not quite as long 
as the first ; the second uropod about two-thirds as long as the first. The 
peduncle of the first long, longer than either rami, much longer than the 
peduncle of the second ; peduncle of the second much longer than that of 
the third. 
Outer ramus of the third uropod much longer than those of the first; 
inner ramus, with single spine, minute. 
Telson : almost square, excavate : four spines on each side terminally, 
two subterminally. 
It appears from the study of the external anatomy that this ampliipod 
comes within the limits of the genus Eucr ang onyx, and from Stebbing’s 
account in “Das Tierreich” to resemble somewhat closely E. vejdovskyi 
Stebbing, which has been taken in wells near Prague. It has accordingly 
been placed in this genus, and near E. rejdovskyi for convenience’ sake 
rather than by way of suggesting its origin, and a name in honour of 
Mr. Noel Roberts has been proposed for it. 
It is in the nature of the uropods that Eucrangonyx robertsi seems to 
possess the chief character of distinction. Other characters suggest that it 
is related to Par acrangonyx compactus , from which, however, it differs in 
possessing normal pleopods, for in P. compactus these appendages are 
univamous ; it is also more distantly related to the genus Neoniphargus 
Stebbing. This cave crustacean, therefore, possesses representatives to 
which it is closely allied in various parts of the world. The difficulty in 
determining exactly what is the form it is most nearly related to is due 
chiefly to the fact that convergence may possibly account for a good deal 
of similarity existing in two or more allied creatures living under similar 
conditions though widely separated. 
Chilton, in his paper on the “Subterranean Crustacea of New Zealand” 
(Trans. Linn. Soc., 2nd ser., Zool., Vol. VI, Part 2, 1894), has pointed out 
the probability of the subterranean Crustacea of that island having been 
derived directly from surface freshwater forms, only indirectly or earlier 
in their history from allied marine animals. On p. 255 ( loc . cit.) he says : 
“No doubt the subterranean Crustacea, as well as the freshwater forms, 
have originally sprung from forms inhabiting the sea, but from a fuller 
array of facts now before us there can be no doubt that they have not been 
derived directly from these, but from a freshwater fauna. Niphargus and 
Grangonyx (Chilton included Par acrangonyx in the genus C-rangonyx') 
may, perhaps, show affinities to marine forms, and there certainly does not 
appear to be any closely allied form now inhabiting the surface freshwaters 
of Europe; but in North America various species of Crangonyx are found 
in surface streams, etc., and the fact that a closely allied form is found in 
the freshwaters of Tasmania seems to show that the genus has probably 
been at one time widely spread in the freshwaters of the globe.” Later, 
he says : “While this conclusion seems to be well founded (in reference to 
the subterranean forms being derived from surface freshwater ones) it by 
no means follows that the subterranean fauna is necessarily derived from 
the freshwater fauna at present inhabiting the surface streams and lakes ; 
indeed, there are several facts which seem to show that some species at any 
rate are derived from a more ancient surface fauna,” 
