88 Dr. W. Baird on British Entomostraca. 



Rami strong and large. Posterior branch having four seta?, 

 three from extremity of last articulation and one from extre- 

 mity of second. Anterior branch has five setae, four disposed 

 as in the posterior branch, and one very long one from extre- 

 mity of first articulation. Antennae pendulous from extremity 

 of beak, broad, and furnished with three short setae at their 

 extremities. Eye large, distinctly areolar, and having its ac- 

 companying black spot near the root of antennae. Shell trans- 

 parent, colourless, smooth, ciliated on anterior margin. Ha- 

 ving only met with this species once or twice I have not taken 

 any note of the intestine, but according to Jurine's figure, it 

 is not convoluted as in the other genera. In general appear- 

 ance this insect resembles very much a Daphnia, and ac- 

 cordingly it has been transferred to this latter genus by Milne 

 Edwards*, though he thinks the species laticornis to be the 

 same as the roseus of Jurine f. 



Hah. Along with Daphnia cornuta and Cy there inopinata, in 

 a pond near Hanwell ; also in a pond at Highgate, but is rare. 



2nd Subgenus. EurycercusJ. " Subquadrangular. Tail 

 very broad, in form of a flat plate, densely serrated." 



1st Sp. Eurycercus lamellatus. PI. II. f. 1 — 8. 

 Syn. Lynceus lamellatus, MiLll. Zool. Dan. Prod. no. 3396 ; Ento- 



most. 73. t. 9. f. 4 to 6. — Monoculus lamellatus, Linn. Gmel. 3008. 



no. 62 ; Manuel, Enc. Meth. vii. 733. no. 62. t. 268. f. 21—23 ; 



FabriciuS; Ent. Syst. ii. 498. — Lynceus lamellatus, Latreille, Hist. 



des Crust. 208; Baird, Trans. Berw. Nat. Club, p. 100; M. Ed- 

 wards, Hist, des Crust, hi. 388. 



This is the largest of all the known species of the Lyncei, 

 being in old specimens fully as large as the Daphnia vetula. 

 Shell of an olive colour, rather square-shaped;* ciliated on an- 

 terior margin, ventricose in centre, and arched on posterior 

 edge of shell. Beak rather blunt and short. Rami very short 

 compared with the size of insect. Anterior branch with three 

 long setae and a short one springing from extremity of last, 



* I have elsewhere mentioned that M. Edwards takes his generic cha- 

 racters of the fam. Daphnidce from the number of branches and articulations 

 of the rami. The genus Daphnia is restricted by him to those species which 

 have two branched rami, with four articulations in one branch and three in 

 the other. Of course, as this insect has only three articulations in each 

 branch, it cannot enter into the genus Daphnia as thus constituted. The 

 Monoculus roseus of Jurine we have not met with, but it differs according 

 to his description from the laticornis in having no areola round the eye, in 

 colour and in shape of antennae ; it is also larger. 



f In Yarrell's 'British Fishes' we have a figure of the roseus at p. 93, 

 torn. ii. copied from Jurine apparently, where it is mentioned as being the food 

 of the fish called the Vendace (Coregonus Willughbii) caught in Lochmaben 

 Loch, Dumfries-shire. 



X From ivgbc broad, and ni^Koc a tail. 



