236 OjST the beitish species of entomostraca 



Yar. obtusifrons, a. 0. Sars, (PI. IX., fig. 22). 



1890. Daphnia galeata, var. obtusifrons, Gr. 0. Sars, Oversigt 



af Norges Crustaeeer med forelobige Bemcerkninger 



over de nye eller mindre bekjendte Arter., p. 33. 



1897. Daphnia galeata, var. ohtusifrons, Richard, Revision 

 des Cladoceres, pi. XXIY., fig. 17. 



The varietal name obtusifrons has been applied by Prof. Sars 

 to a form of D. galeata without cephalic spine, which he has 

 found during the early months of summer only. The figure 

 given by M. Richard closely agrees with an interesting form of 

 B. galeata taken by the Rev. Canon Norman in Loch Ness, of 

 the head of which I give an outline (plate IX., fig. 22). 

 The beak, it will be seen, is extremely wide and prominent ; 

 though the head is small in proportion to the body. I have not 

 been able to detect any eye-spot, but this is liable to disappear 

 by prolonged maceration in spirit. In general shape the animal 

 resembles the variety major of B. longispina, but it is very 

 much smaller, almost colourless, and has no basal dilatation of 

 the terminal spine. The number of caudal teeth is about twelve. 

 Length, 1*6 mm. 



I can scarcely think that this form is a permanent one, or that 

 it represents more than a transitory condition dependent on 

 growth or some peculiarity of environment, but without an 

 accurate knowledge of life-history it is impossible to arrive at a 

 satisfactory conclusion as to the relations of the almost innu- 

 merable forms which, for the present, must be distributed under 

 the specific names of longispina, galeata, lacustris, etc. In the 

 case of the Loch Ness gatherings, many other forms are to be 

 found mixed up with obtusifrons. 



Genus HYALODAPHNIA, Schoedler. 



Hyalodaphnia Jardinii, (Baird), (PL X., figs. 12-15). 

 1857. Dap/mia Jardinii, Baird, " On the food of fresh- water 

 Fishes," (Edinb. New Philosophical Journal, N. S., 



vol. YL, part 2). 



1867. Daphnia cucullata, P. E. Miiller, Danmarks Clado- 



cera (Naturhistorisk Tidsskrift III.), p. 120, 



pLL, fig.23. 



