ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 69 



parallel in Selachians, where a FUotrema, a Pristiophorid shark described 

 by C. Tate Regan, lias six branchial arches instead of the usual five, but 

 is evidently a very highly specialized form, derivable from some ancestor 

 like Fristiophorus, with the normal number of arches. 



f. Crustacea. 



Habits of Atya, Caridina and Myctiris.* — R. P. Cowles has 

 studied the feeding habits of Afy// molluccensis and some species of 

 Caridina from streams in the Philippines. In both genera the clielEe 

 of the first and second legs are peculiarly shaped and are provided with 

 dense groups of setae like a camel's hair-brush. A microscopic examina- 

 tion of the setse shows that each has finer setas growing from it. 

 Observations on Atya show that brushes spread out to make wide open, 

 almost funnel-shaped strainers, the larger open ends of which are 

 directed towards the stream. They collect small organisms and particles 

 in the water. Each chela has two brushes or strainers, making eight in 

 all. When a pair of strainers has collected enough, the setag become 

 g'-ouped into a single brush, the chela turns backward on its base 

 through almost 180\ and the brush is applied to the mouth where the 

 food is extracted. The last part of the operation takes less than half a 

 second, and then the chela returns to its former position. 



In Caridina the chelse have a different form, and the sette are 

 shorter and less numerous. They do not seem to spread out to form a 

 strainer. The animals are mud-feeders ; they sweep the surface with 

 their brashes, and apply these to their mouth. 



Specimens of Myctiris lonyicarpus Latreille move about in armies on 

 exposed sand flats at low tide. The grey-blue, almost spherical, body 

 is of about the size of a large cherry. All the individuals move in the 

 same general direction. They are continually scooping up sand with 

 their chelipeds and smearing it over the mouth parts, probably feeding 

 on minute organisms and on detritus. When alarmed they sink into 

 the sand with astonishing rapidity — about two or three seconds. Each 

 digs with the legs of one side and rotates at the same time, so that the 

 digging follows a spiral. 



Fresh-water Crab from Australia and New Zealand.j — Charles 

 Chilton describes a small fresh-water crab, Hynienosoma lacustris 

 Chilton { = Elameaa (?) lacustris Chilton), which is known from three 

 localities in the north of New Zealand, from Norfolk Island, Lord Howe 

 Island, and from two localities in Victoria, Australia. It is a true fresh- 

 water species widely distributed in localities now separated by broad 

 tracts of ocean. Judging from its distribution, Chilton regards the 

 species as of very considerable antiquity. In one specimen from Lake 

 Takapuna, Anckland, there were about twenty zoeae lying free under 

 the abdomen. 



* Philippine Journ. Sci., x. (1915) pp. 11-16 (3 pis. and 2 figs.). 

 t Trans. New Zealand Inst., xlvii. (1915) pp. 316-20 (1 fig.). 



