442 D. J. SCOURFIELD, SYNOPSIS OF THE KNOWN SPECIES OF 



A. aflanis Leydig. 



Alona quadranyiddris Baird (in part) (1). 



Lijnceus quadrangularis Norman & Brady (in part) (17). 

 This seems almost if not quite as common as the foregoing 

 species, and often occurs with it. 



A. tenuicaudis Sars. 



Lynceus teyiuicaudis Norman & Brady (17), Hodgson (10). 

 A rather rare species, but well distributed. 



A. costata Sars. 



Lynceus costatus Norman & Brady (17), Hodgson (10). 



A. guttata Sars. 



Lynceus guttatus Norman <fe Brady (17), Hodgson (10). 



A. intermedia Sars. 



A. mglecta T. Scott (20, 23). First described in (23) Part I. 

 This species has only been found in Scotland, where apparently 

 it is not at all uncommon. 



A. rectangula Sars. 



A. intermedia Scourfield (25, 26), Scott (20). 



Lynceus intermedins Hodgson (10). 

 Probably a moderately common species all over the British 

 Isles, but often overlooked owing to its small size. 



A. elegans Kurz. 



I am indebted to Canon Norman for specimens of this pretty 

 little species. As it is not to be found in the " Cladocera 

 Sueciae," sketches are given of the shell (fig. 13), showing the 

 very characteristic close striation (there are about sixty striae 

 on each valve), and of the post-abdomen (fig. 14). The teeth on 

 the latter are not all simple, as stated by Kurz, but some are 

 compound. Length about -^^ inch. Roadside pond near Staithes, 

 Yorkshire. It has not been previously recorded as British. 



A. rustica T. Scott (23 Part I.). 



This seems to be distinct from any of the species given in the 

 " Cladocera Sueciae." It is mainly characterised by its post- 

 abdomen, of which a drawing is given in fig. 10. It will be 

 seen that the inferior angle is very much produced, although well 

 rounded, and that the teeth on the dorsal edge are robust and 



