18 
SPOLIA ZEYLANICA. 
abdomen.” The third and fourth particulars, however, are only 
claimed as differences, because they are not mentioned in the 
description of Sphceroma vastator. But no inference can be drawn 
from the absence of mention to the absence of a character. 
Writers leave many points unmentioned from carelessness, for fear 
of being prolix, or through failing to observe them. The features 
here in question are not of the highest importance and in some 
specimens cannot easily be discerned. In the dorsal view of 
Sphceroma destructor itself they are not indicated. 
Our knowledge of Sphceroma terebrans is derived from the 
figures which Bate gives of the uropod and the mandibular palp, 
and two comparative statements which those figures are designed 
to illustrate. He does not allege that the outer ramus of the 
uropod differs by its shape in the two species, but appeals to the 
u short fine cilia” in S. vastator as offering a ready contrast to 
the “ long and coarse hairs” in S. terebrans . The small import¬ 
ance of such a distinction may be judged from the circumstance 
that Miss Richardson mentions neither the occurrence nor the 
absence of either cilia or hairs in this part of S . destructor . 
The remaining contrast is of a higher grade. To justify a 
discriminating name for the isopods from Madras, Bate says : “ A 
close examination is required to distinguish a specific character 
separating these from the Brazilian specimens ; and I think that 
the only one to be relied upon is that the pointed and hook¬ 
shaped termination of the appendage of the mandible in Muller’s 
specimens is represented in those from Madras by a flat broad 
joint. I therefore think that, minor variations being taken into 
consideration, together with the distance of the two habitats, we 
do not err in considering the following a distinct species from 
that found by Fritz Mtiller.” For S. vastator he figures a normal 
mandibular palp, fairly in agreement with what is found in the 
specimens from Ceylon and with the figure which Miss Richardson 
gives of this appendage in S. destructor. But for S. terebrans the 
figure exhibits a four-jointed palp, which can only be accepted by 
one who is willing to cry credo , quia impossibile . There cannot 
be the slightest doubt that the artist has been the victim of some 
ocular deception, “ the pointed and hook-shaped termination” 
not being a joint at all, but merely the terminal spine or spines of 
the third joint, the true shape of which has been obscured by the 
angle at which it was viewed. 
Passing now to the specimens from Ceylon, I find them in so 
close an agreement with the description and figures given by 
Miss Richardson for S. destructor , that they might certainly fall 
to that designation but for the high probability that S. destructor 
