412 Dr. Baird on some new Genera and Species 
Berw. Nat. Club’ for 1845, I have proposed forming a distinct 
family for receiving all those species of the genera Daphnia and 
Iynceus of Miiller that have the antennules pendulous from the 
beak. In the ‘Ann. Mag. Nat. Hist.’ xi.p.87, I have arranged the 
genus Macrothriz, provisionally, under the fam. Lynceide, as it 
possesses only three articulations to each joint of the large an- 
tenn, and has also the black point in front of the eye. I have 
now ascertained however that it has not the articulated abdomen 
nor the convoluted intestine that form such distinguishing marks 
in the Lynceide, being in these respects formed like the Daphnide. 
It cannot thus be received into that family, and as in its position 
of antennules it agrees with the D. cornuta, I now propose ar- 
ranging it in the same family. The two families and genera will 
be thus characterized :— 7 
Fam. I. DAPHNIDZE. 
Two pairs of antenne ; superior very small and situated under 
the beak, inferior large, two-branched, and used as organs of lo- 
comotion. Five pairs of feet. Head prolonged into a more or 
less obtuse beak. Lye single, large. Intestine straight. 
This family contains two British genera, Daphnia and Sida. 
(Trans. Berw. Nat. Club, 1845, p. 148.) 
Fam. II. BOSMINIDZ. 
Two pairs of antenne ; superior longer than in preceding fa- 
mily, and pendulous from or articulated to the extremity of the 
beak. In other respects as in Daphnide. 
This family contains two British genera, Bosmina and Ma- 
crothriz. 
Gen. 1. Macrorurix, Baird, Ann. Mag. Nat. Hist. xi. p. 87. 
Superior antenne flat, consisting of only one articulation. 
Inferior antenne large, two-branched, each branch having three 
articulations. Second articulation of anterior branch provided 
with a very long seta. Eye accompanied with a black spot. 
Gen. 2. Bosmina, Baird, Trans. Berw. Nat. Club, 1845. 
Superior antenne long, curved, cylindrical, and consisting of 
many articulations. Inferior antenne large, two-branched, one 
branch having four, the other three articulations. 
Sp. 1. Bosmina longirostris. Pl. IX. B. f. 1. 
Syn. Lynceus longirostris, Miiller, Entom. 76. t. 10.f. 7, 8.—Mono- 
culus cornutus, Jurine, Hist. Nat. des Monoc. de Geneve, 142. t. 14. 
f. 8-10.—Daphnia cornuta, Desmarest, Consid. gén. Crust. 375 ; 
Baird, Ann. Mag. Nat. Hist. i. 257.t.9.f.15; M. Edwards, Hist. 
Nat. Crust. iii. 382.—Bosmina cornuta, Baird, Trans. Berw. Nat. 
Club, 1845. 
