New Cladocera of the English Lakes. By Conrad Beck. 783 



The alimentary canal is simple. The labrum covers the 

 entrance of the narrow oesophagus, which leads into the stomach 

 dilated anteriorly; it then runs down without convolution to the 

 anus between the terminal spines ; the rectum is muscular, and 

 continually contracting. The heart is at the back, below the divi- 

 sion of the head and body. The matrix enlarges laterally, and this 

 helps to give the animal a broad appearance. The size of different 

 specimens of Latona varies considerably; it is often as large as 

 1-1 0th in. in length. 



Ai)pendages. — The first antennae (fig. 11) are attached to the 

 head near the pigment-spot. They consist of a small joint, fol- 

 lowed by a long flagellate segment fringed with fine hairs, which 

 are thickly bunched at the base of the segment. This pair of ap- 

 pendages is almost alike in both sexes. The second pair of antennae 

 (fig. 12) have a broad stout segment with apparently three branches 

 at its end. On closer examination, however, it is seen that there 

 are only two branches, but that the basal segment of the posterior 

 branch is enlarged and drawn out into a leaf-like portion, as seen 

 in fig. 12. This is found in no other Cladocera. The appendage 

 corresponds to that of Daj)hneUa. The anterior branch, as in 

 Daphnella, is three-jointed ; the first joint is small, the second and 

 third are larger, and carry setae at their ends. The posterior 

 branch in each case consists of two joints ; in Daphnella both are 

 fringed with setae on their anterior edge, whilst in Latona the first 

 joint is, as it were, drawn out, and both it and the second are thickly 

 beset with setse. 



The mandibles (fig. 13), maxillae (fig. 14), and six pair of feet 

 are very similar in construction to those of Sida. The first pair is, 

 however, considerably longer. Each of the terminal spines of the 

 post-abdomen has only one small supplementary spine at its base. 



Latona setifera more clearly resembles Sida and Daphnella 

 than any others of the Cladocera, and belongs to the family of the 

 Sididae. 



Distribution. — This species, unless disturbed, lies on its back 

 at the bottom of the water amongst the reeds. In order to obtain 

 specimens, a net must be dragged along so as to scrape the bottom. 

 I found it at a depth of about three or four feet. I have at present 

 only found it in Grasmere and Kydal "Water, although I think it 

 would probably be found in the other lakes if properly hunted for. 

 They are not common; I found none in May, and only small 

 quantities in September. 



Besides these three species I found many other interesting 

 forms, including Strehloceros serricaudafus, which was found for 

 the first time in England last year by the Eev. A. M. Norman. 

 At the top of Langdale Pike, a height of 2400 feet above the sea, 



