Section D. 
BIOLOGY. 
President of the Section: Professor A. P. Thomas, M.A., F-L.S. 
1—ON SOME. POINTS IN THE MORPHOLOGY OF 
ASTACOPSIS BICARINATUS. 
By J. StepHen Harr, M.A., B.Sc., University of Melbourne. 
[ Abstract. | 
THE common crayfish of the ponds and waterholes of Victoria, 
known as Astacopsis bicarinatus, or popularly as the yabbie or 
yabber crayfish, is a member of the family Parastacide, separated 
by Professor Huxley from the northern crayfishes on account of 
the absence of a well-developed lamina on the podobranchie, of 
appendages on the first abdominal segment, and of a transverse 
hinge dividing the telson. But although placed ina different 
sub-family, our Astacopsis resembles very nearly the European 
Astacus, and is substituted for it in our university courses and 
elsewhere as a representative of the bigher crustacee. The aim of 
this paper is to serve as a supplement to the well-known text- 
books—such as Huxley’s volume, in the International Series, or 
Marshall and Hurst’s Practical Zoology—by pointing out what 
differences are to be looked for in the general anatomy of the two 
genera. 
The external form is described by Professor McCoy in the 
Prodromus, decade iii., plate 29, under the name of Astacoides 
dicarinatus, and further details are given in decade xvi., plate 160. 
To this description it should be added that the first abdominal 
segment has pleura as large, in proportion, as the other segments, 
and not concealed, as in Astacus, by those of the second segment. 
The colour, as Professor McCoy points out, is very variable, the 
forceps alone being constantly blue, with red joints. The mem- 
branous parts of the last appendages of the abdomen are said by 
him to be constantly brown, but I have found them much more 
often of a bluish colour. 
Appendages.—The thoracic and cephalic appendages are identical 
with those of Astacus, but those of the abdomen are very 
different. As already stated, there are none on the first segment. 
