A HISTORY OF LEICESTERSHIRE Mr. Garnar, making, after some deductions suggested by Mr. Scourfield, a total of thirty species of Cladocera to the credit of this county. In this sub-order there are two principal divisions, the Calyptomera and the Gymnomera. It is only with the former that we are here concerned. The name implies that the feet are for the most part covered by the carapace. The division contains two tribes, the Ctenopoda, comb-footed, and the Anomopoda, differentially footed. In the former there are six pairs of feet, all thin and leaf-like, and except the last pair nearly alike in structure, not prehensile, having the inner branch furnished with plumose setae in comb-like arrange- ment. 11 There are two families, one of which, the Sididae, contains the species called by Mr. Garnar Diaphanosoma brandtianum. This name was given it by S. Fischer in 1850, but as it had been earlier named Slda brachyura by Lievin in 1848, it must now stand as D. brachyurum^ implying that this little sylph has a particularly short tail and shares with several of her sisters a generally diaphanous structure. In this genus the upper branch of the second antennae is two-jointed and the lower three-jointed, whereas in Sida the case is just the reverse. The Anomopoda, to which most of our Leicestershire cladocerans belong, have five or six pairs of feet, not in fraternal agreement, the first two pairs being more or less prehensile, without the foliaceous character of the following pairs. This tribe is distributed over four families, the Daphnidae, Bosminidae, Macrotrichidae, and Chydoridae, for discriminating which the articulation of the natatory antennae and the intestine supply some useful, but not wholly decisive, guidance. In the fourth family both branches of the second an- tennae are three-jointed, in the first and third families one branch has four, the other only three, joints ; but the small family of the Bosminidae, with only two genera, distinguishes one of them, Bosminopsis, by its having the swimming-organs jointed as in the Chydoridae, from the companion genus Bostmna, which in this respect agrees with the other two families. The number of these joints, therefore, will not in any case absolutely determine the family. Upon having recourse to the other character, we find that the intestine in the Daphnidae has two coecal appendages in front, but has no loop, in the Bosminidae it has neither loops nor coecal appendages, in the Macrotrichidae it has coecal appendages rarely, and sometimes a loop, but . sometimes not, while lastly, in the Chydoridae it always has a median loop, coecal appendages in front rarely, a single such appendage behind often. When both characters are combined there is still some confusion possible between the Daphnidae and some members of the Macrotrichidae. But this chance is much diminished by taking into account the first antennae, which in the female of the Daphnidae are short and almost rigid, except in the genus Moina, whereas in that genus and throughout the Macrotrichidae they are long and mobile. As it happens no species of Moina is included in our present catalogue, but there are four other genera of the same family with which we have to deal, Daphne or Daphnia, O. F. Miiller; Scapholeberis, Schodler; Simosa, Norman; Ceriodaphnia, Dana. In the first three there is a distinct rostrum which is wanting in the fourth. The head is carinate above in the first, but convex and not carinate in the second and third, and, to dis- tinguish these two, it must be noted that the hinder and lower margins of 11 Lilljeborg, Cladocera Sutciae, 14 (1901). 100
