ON BOSMINTD^, MACB0THEICID.2E, ETC. 395 



that part which covers the feet) reticulated. Head very up- 

 right, hood-shaped, and produced into an acute rostrum; ante- 

 rior antennae much shorter than the head ; posterior antennae of 

 moderate length. Eye of moderate size ; eye-spot nearly as large 

 as the eye, situated midway between it and the extremity of the 

 rostrum. Abdomen of moderate size, having the superior margin 

 rounded off to the base of the claws, there is thus no supero-pos- 

 teal angle ; marginal spines (from ten to twelve) small ; claws 

 long and slender, gently curved, with a minute spine springing 

 from the base. Length, ^-th of an inch. 



The description given by Dr. Baird of his Alona ovata for the 

 most part well accords with the characters of the present species, 

 especially the statements that "the shell is striated; stria waved 



longitudinally Eye areolar, anterior black spot large the 



head is erect, as in A. quadr angular is ;" but on the other hand, 

 the examination of the figure given, and the dimension of the 

 species, "in size it is rather larger than the A. quadr angular is" 

 leave us in doubt as to whether the species described by him is 

 synonymous or not with L. rostratus. 



L. rostratus has been observed on the Continent in Prussia, 

 Germany, Sweden, and Norway. The only British habitat we 

 know for it is the East Lake at Belsay, Northumberland. The 

 lake in question is only a small piece of water, yet is sufficiently 

 large to afford an entirely different Entomostracan Fauna in dif- 

 ferent parts. The authors visited this lake together, and while 

 the one (A. M. N.) procured his gathering of Entomostraca at the 

 extremity of the lake, the other (G. S. B.) was fishing about the 

 middle of its length. On returning home and examining the pro- 

 ceeds under the microscope, while the former found that he had 

 nothing of value, the latter discovered that he had taken not only 

 such rare things as Macrothrix laticornis and Ilyocryptus sordidus, 

 but also two interesting additions to the British Fauna, namely, 

 Monospilus tenuirostris (Fischer), and Lynceus rostratus (Koch). 

 The circumstance impressed more deeply a lesson, which was not 

 then learnt for the first time, that it is very easy to procure 

 gatherings again and again from a piece of water, of even very 

 limited area, and yet to remain very imperfectly acquainted with 



