Part III — Thirteenth Annual Bcport. 



189 



NOTES ON THE SPECIES REPRESENTED BY THE DRAWINGS 

 ON PLATE V. By Thomas Scott, F.L.S. 



Daphnia longispina, Muller, Plate V. fig. 1 . 



This was the only species of Daphnia observed in the lochs of Shet- 

 land recently examined. It is distinguished from its close ally, Daphnia 

 pulex, by the elongate posterior spine and by the absence of teeth on 

 the post-abdominal claw. 



Alona costata, G. O. Sars, Plate V. figs. 2 and 12. 



Alona costata is a small species. Tho size of the specimen figured is 

 •65 m.m. of an inch). It somewhat resembles a small form of Alona 

 quadrangular is, especially in the form of the post-abdomen ; but on care- 

 fully comparing the two together they are seen to differ in several respects, — 

 the post-abdomen in A. costata is broader in proportion to its length than 

 that of A. quadrangular Is, and the terminal claw has no supplementary 

 setae at the base as in that species. Drawings of Alona quadrangular is 

 and of its post-abdomen are given to show some of these differences (see 

 figs. 2 and 13). Fig. 11 represents the male of A. quadrangularis ; fig. 15 

 shows the male post-abdomen, and fig. 25 one of the first feet with its 

 hook-like appendage. 



Alona neglecta, n. sp., Plate V. figs, i and 18. 



This Lynceid somewhat resembles Alona quadrangularis in general 

 appearance, but is more decidedly truncate at the posterior end. The 

 extremity of the post-abdomen is broadly truncate, and the supero-posteal 

 angle boldly rounded ; immediately anterior to this the width of the 

 post-abdomen decreases, the superior margin curving slightly inwards and 

 then extending in a nearly straight line to the superior marginal angle. 

 The terminal claw is moderately slender, and the secondary claw is about 

 one-third the length of the primary one. Length *47 mm. (-^ of an inch). 

 I have been unable to identify this Alona with any described species. 



Alona rustica, n. sp., Plate V. figs. 5 and 17. 



Seen from the side, subquadrangular in outline, superior margin gently 

 curved, posterior margin nearly straight and slightly sinuate, posterior 

 end subtruncate. The width is equal to fully two-thirds of the length. 

 Post-abdomen robust, the supero-posteal angle is produced prominently 

 backward and is narrowily rounded ; from thence the superior margin 

 extends anteriorly and outwardly in a nearly straight line to a distance 

 from the posteal angle equal to rather more than the length of the 

 terminal claw; the margin then bends inwards and forms a shallow 

 concavity, bounded anteriorly by a small papilliform process, as shown 

 in the drawing (fig. 17); at this point the width of the post-abdomen is 

 almost twice what it is at the posterior end. The terminal claw is short 

 comparatively, and very stout, its secondary appendage is very small. 



