Carcinological Fauna of India. 125 
or may be intermediate in character. The gill-plumes vary in number 
from 20 to 8 on either side. 
I follow Professor Boas, withont hesitation, in placing the Dromiacea at the 
base of the Brachyura; and I further think that no one who has access to a good 
spirit-collection of the two groups in question can read M. H.-L. Bouvier’s clever 
paper, cited above, Sur Vorigine Homarienne des Crabes, without accepting the 
opinion of the latter author—an opinion previously suggested, as the author states, 
by Huxley—that the Dromiacea are the directly-connecting link between the Crabs 
(Brachyura vera) and the Homaride. 
The Dromiacea may be divided into two groups, which seem to me 
to have something more than family value, namely, the Dromiidea and 
the Homolidea, each of which has retained certain primitive characters 
while following its own line of evolution. 
Tribe I. Dromippa. 
Dromiens, Milne Edwards, Hist. Nat. Crust. II. 168. 
Dromidz, Henderson, Challenger Anomura, p. 2. 
Dromide et Dynomenidz, Ortmann, in Bronn’s Thier Reich, V. ii. Arthropoda, 
p. 1155. 
Carapace sometimes longer than broad, often broader than long, 
without linea anomurica. 
Eyes and antennules almost always (Homolodromia is the only 
exception) retractile into common orbito-antennulary pits, the lower 
wall of which is formed about equally (1) by the basal joint of the 
antennule itself, (2) by the basal joint of the antenna, and (3) by a 
sub-orbital spine or dentiform lobe. 
These orbito-anteunulary pits very often show traces of a sub- 
division into two fosse, one for the antennule the other for the eye—the 
boundary between the two fosse often being a tooth or a sort of fold in 
the upper margin of the “ orbit.” 
Eye of the ordinary form, situated at the end of a short stout eye- 
stalk, the basal joint of the eye-stalk being inconspicuous. 
Hpistome triangular, its apex usually being in close contact with 
the deflexed tip of the front. Vault of the palate of good depth. 
External maxillipeds usually opercular, sometimes subpediform. 
Fingers of the chelipeds generally short, stout, channelled along 
their opposed surfaces, and strongly calcified in their distal half. 
Sternum of the female traversed longitudinally, in part or in 
almost all of its extent, by a pair of special grooves that sometimes end 
in special tubercles. 
The abdomen of both sexes consists of seven separate segments. 
Very often a pair of small lateral plates—the rudiments, probably, of 
573 
