A STUDY IN CARCINOLOGY. 73 
of burrowing in the sand for protection and concealment. A decapod 
crustacean which hnbitually passes a large part of its existence buried in the 
sand, must undergo a considerable modification of its respiratory arrange- 
ments, and I liave attempted to give an intelligible account of these modifi- 
cations in the various members of the Grj'mnopleura. In the end they lead, 
as is natural enough, to the suppression of the inhalant current at the hind 
end of the thorax and to the substitution of inhalant currents in the antennary 
region. I have said, in the earlier part of this memoir, that the Gj'mnopleura 
are crabs by definition. They retain so many Macrurau features that they 
cannot be said to be crabs by ancestry, and there is one small Macruran 
feature which I have omitted to mention before because I only recognised it 
when the greater part of this paper was written. The statocyst, usually 
closed in the Brachyura, is open in the Gymnopleura. Certainly so in Ranina, 
Notosceles, and Lyreidus, but 1 have not been able to satisfy myself of the 
existence of the aperture in all the species examined because the antennules 
are very small and I have not been able to cut sections. The position of the 
aperture of tbe statocyst is clearly shown in fig. 34 for Ranina. 
I must conclude with a description and definition of the new genus and 
species Notosceles Chinimonis. 
There can be little doubt that Raninoides serratifrons of Henderson (36) 
belongs to the genus Notosceles and not to Raninoides, but his species, 
from Ceylon, is different to mine. He mentions another example of 
serratifrons from Holothuria Bank, N.W. Australia, as being in the collec- 
tions of the British Museum of Natural History, but I was unable to find 
it there. There are considerable differences between Notosceles and 
Raninoides, many of which have been referred to in the course of this 
paper. 
Notosceles, nov. gen. 
Carapace ovate, convex from side to side, minutely puuctate or smooth 
for the most part but granular towards the frontal region; fronto-orbital 
border little more than half as wide as the broadest part of the carapace ; the 
frontal region marked off by a slight transverse ridge joining the bases of 
the extra-orbital spines ; the rostrum pointed, fairly prominent with two 
flat lateral and basal (eeth. Ocular peduncles rather short, their terminal 
joints inflated, their cornese of moderate size. Antennal peduncle short and 
broad, the flagellum small. Merus of the third maxilliped little more than 
half as long as the ischium. The second and third sternal elements of the 
sternal shield (sterna xi & xii) broad and convex in front, but narrowed 
posteriorly so that the bases of the first as well as the second pereiopods are 
approximated to the middle line. Last pair of pereiopods reduced in size, 
situated above and in front of the penultimate pair, their dactyli small, oval. 
