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Part III. — Thirteenth Annual Report 



The hinder part of the superior margin of the post-abdomen is armed 

 with strong conical teeth, and a fringe of small setae borders the shallow 

 concavity (fig. 17). Length -41 mm. (^j- of an inch). The carapace of 

 Alona rustica, is sometimes ornamented with coarse pit-like markings 

 (guttm) somewhat like those of Alona gutatta, but coarser. I have also 

 been unable to identify this with any described species. 



Alona guttata, G. 0. Sars, Plate V. figs. 8 and 21. 



This is a very small species. The length of the specimen represented 



by the figure is 35 mm. of an inch). The form of the post-abdomen 



(fig. 21) is quite sufficient to distinguish this from any of the other 

 British Lynceidae. 



Chydorus barbatus (G. S. Brady), Plate V. figs. 7 and 19 ; and 

 figs. 8 and 21. 



Figs. 7 and 19, and figs. 8 and 21, represent what appear to be two 

 forms of the same species. Seen laterally the carapace is nearly quad- 

 rangular and thickly covered with little pits (guttse). The post-abdo- 

 men is comparatively short. The supero-posteal anglo is rounded and 

 provided with a number of small setae. The length of the specimen 

 represented by fig. 7 is '38 mm. of an inch), while that represented 

 by fig. 8 is '43 mm. (-^g of an inch). 



Chydorus (?) ovalis, Kurz, Plate V. figs. 10 and 23. 



This Lynceid appears to be the Chydorus ovalis of Kurz. Seen 

 laterally the outline is quite different from that of Chydorus sph&ricus, of 

 which figures are also given for comparison (see figs. 9 and 22). The 

 size of Chydorus ovalis represented by the figure is - 36 mm. (y 1 ^ of an 

 inch), while the specimen of Cliydorus sphsericus is *4 mm. (^ of an inch). 



Alonella exigua t G. O. Sars, Plate V. fig. 14. 



Alonella exigua was somewhat scarce in the Shetland lochs, but being 

 a small species it is easily overlooked. Fig. 14 shows the post-abdomen 

 of a specimen from Loch of Huxter. 



Alonopsis elongatus, G. O. Sars, Plate V. figs. 20 and 24. 



The drawings referred to represent the post-abdomen of a male specimen 

 (fig. 20) and (fig. 24) the hook-like appendage of one of the first feet in 

 the male. 



I have much pleasure in acknowledging my indebtedness to Prof. G. F. 

 Brady, and Mr A. J. Scourfield of London for assistance in the identifica- 

 tion of some of the more obscure species of Oladocera. 



