ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
203 
(fam. Myrmecidae), is from Ceylon; the second, Friula Walladi (fam. 
Gasteracanthidae), was found by Dr. A. R. Wallace at Sarawak many 
years ago. It is a remarkable form, the exterior angle of the diamond- 
shaped abdomen being prolonged on each side (for more than the width 
of the abdomen) into a strong cylindrical spine-like projection, directed 
rather backwards, and enlarged or clavate at the extremity, ending 
in a group of six or seven small conical prominences. The author also 
gives an account of the males of Labdacus monastoides Cambr. and 
StepJmnojpoides brasiliana Keys, the females only having been hitherto 
described. 
Epizoic Mite on an Ant.* — M. Ch. Janet describes the occurrence 
of a mite, Antennophorus Uhlmanni Haller, beneath the head and on the 
sides of the abdomen of Lasius mixtus Nyl. It feeds on nutritive fluid 
disgorged— willingly it would seem — by the ant. 
€. Crustacea. 
Notes on Crabs.f— Mr. W. Garstang discusses the function of the 
antero-lateral denticulations of the carapace in sand-burrowing crabs, 
such as Batliynectes longipes and Atelecyclus heterodon. They subserve 
a sieve-like function, and the extent of the denticulated area corresponds 
with the extent of the inhalant gap between the carapace and the cheli- 
ped, when the latter appendage is approximated to it in the flexed 
position. In the sand-burrowing crabs with these denticulations, the 
chelipeds" act as organs temporarily subservient to the respiratory pro- 
cess by providing a broad oj^erculum to the exostegal channel. 
Mr. Garstang also describes the systematic features, habits, and 
respiratory phenomena of Portumnus nasutus Latreille, which has not 
been previously recorded as an inhabitant of British seas. Again he 
shows the utility of apparently trivial specific characters. 
Development and Species of Sergestes.t — Dr. H. J. Hansen gives 
a brief account of this genus, in regard to which more complete observa- 
tions are much to be desired. Of the 50 (or 60) hitherto described 
species, only about 20 have been established on sexually mature forms, 
and almost all the other species are larval stages, some of them of species 
previously established on adult specimens. Of the 20 species founded 
on adult specimens, 2 are excluded for good reasons, and 4 are cancelled 
as synonyms. 
When a species is mature, the male always possesses a large petasma, 
and — so far as we know — a peculiar development of the exterior flagellum 
of the antennulae. In all larvae ( 3Iastigojpus ) the eyes are yellowish or 
whitish, and black pigment, when present, is found only in the interior, 
and very remote from the cornea ; while in the adults the eyes are totally 
black. 
With one exception ( S . arcticus) all the species are found in tropical 
and sub-tropical seas, to lat. 42°-43° N. in the Atlantic. All the larvae 
are essentially surface forms, but at least two-thirds of the species in- 
habit the depths of the sea when mature. 
* Comptes Kendus, cxxix/(1897) pp. 583-5 (1 fig.). 
t Journ. Marine Biol. Ass., iv. (1897) pp. 396-407 (2 figs.). 
X Proc. Zool. Soc. London, 1896, part 4 (published 1897) pp.' 936-70. 
* p 2 
