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). 



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