Dr. W. Baird on British Entomostraca. 93 



tennae conical-shaped. Intestine convoluted once and nearly 

 a half, but not so very distinctly visible as in the other ge- 

 nera. Eye areolar. Body rounded at upper extremity as in 

 Acroperus harpce. I had some doubts at first as to this being 

 identical with the striatus of Jurine. In his figure the beak 

 is blunter and the tail shorter and rounder-shaped than in my 

 specimens. He gives it the name of striatus with a doubt, 

 and remarks, "if this species be the truncatus of Miiller, 

 as we may presume it is, it must be confessed that its specific 

 name is improper; for the shell is not truncated, it is ob- 

 liquely striated and strongly ciliated*." 



It is evident that Jurine could never have seen the trunca- 

 tus of Miiller, and the quadrangularis seems also to have been 

 unknown to him, for the difference between his species (the 

 striatus) and Midler's truncatus is so great and evident that 

 they cannot be mistaken for each other; while the similarity 

 between it and the quadrangularis is so evident, that notwith- 

 standing the slight differences mentioned above, I have little 

 or no hesitation in referring them both to the same species. 



Hab. Ditch near Richmond, opposite Isle worth church ; 

 pond at Osterly Park and near Hounslow ; u in the Pease 

 burn, and in a pool on Beaumont water at Yetholm," — 

 Trans. Berw. Nat. Club. 



2nd Sp. Alona reticulata. PI. III. f. 12. 



In size this is perhaps the smallest of all the species of this 

 family, being rather smaller than the Acroperus nanus. Shell 

 of a quadrangular shape, rounded a little posteriorly, and 

 nearly straight on anterior margin, which appears free from 

 cilia. The lower margin is obtuse, and the whole shell is 

 closely reticulated. Beak prominent and long, projecting 

 upwards, rather blunt. Rami rather slender ; anterior branch 

 provided with four setae, one shortish from second articula- 

 tion, and three long and stout ones from last. Posterior 

 branch has three from last joint only. Tail rather tapering 

 towards the extremity, and serrated on inferior margin. Eye 

 large for the size of the animal, areolar. Intestine convo- 

 luted, but it is not very easily seen, from reticulated surface of 

 shell. One ovum. 



Hab. Pond near Southall, Middlesex : Sept. 1842. 



7th Subgenus. PLEUROXusf. "Anterior margin prominent 

 on the upper portion ; the lower part being truncated, or as it 

 were cut sharp and straight. First pair of feet very large." 



1st Sp. Pleuroxus trigonellus. PL III. f. 13. 

 Syn. Lynceus trigonellus, Mull. Zool. Dan. Prod. no. 2395 ; Ent. 

 * 1. c. p. 154. f From ?r*su(>6v a side, and 6%v; sharp. 



