292 Part III. — Ninth Annual Report 



A large and easily identified species. The post-abdomen is " a broad 

 flattened plate with a very closely serrated margin." 



Acroperus, Baird. 



Acroperus harpa, Baird. 



1835. Lynceus harpce, Baird, Trans. Berw. Nat. Club, vol. i. p. 100, pi. ii. 



fig. 17. 

 1841. Lynceus leucocephalus, Koch, Deutsch. Crust, Myriap. u Arach., p. 36, 



pi. x. 

 1850. Acroperus harpce, Baird, Brit. Entom., p. 129, pi. xvi. fig. 5. 

 1884. Acroperus leucoceplialus, Herrick, loc. cit., p. 81, pi. E, fig. 5, pi, i. 



fig. 9. 



This species is generally distributed and moderately common. For full 

 description, see Baird, loc. cit., p. 129. 



Alonopsis (G. O. Sars). 



Alonopsis elongata, G. 0. Sars. 



1848. Lynceus macrurus, Lievin, Die Branch. derDan. Geg., p. 41. pi. x. fig. 1. 

 1862. Alonopsis elongata, G. 0. Sars, Om. de i Orneg. af Christi. forekom. Clad. 



Andet Bidrag., p. 41. 

 1867. Lynceus elongatus, Nor. and Brady, loc. cit,, p. 376, pi. xviii. fig, 1, 



pi. xxi. fig. 2. 

 1884. Alonopsis elongata, Herrick, loc. cit., p. 85. 



This species is larger than Lynceus quadrangularis, for which it has 

 probably sometimes been mistaken. It is easily distinguished " by the 

 presence of the three spines, which spring from the terminal claws of the 

 abdomen, and which are very conspicuous under the microscope." It does 

 not seem to be a rare species. 



Leydigia (Kurz). 



Leydigia quadrangularis (Leydig). PI. ii. figs. 5, a-b. 



1860. Lynceus quadrangularis, Leydig, Naturges. der Daphn., p. 221, pi. viii. 



fig. 59. 

 1863. Alona leydigii, Shcedler, Neue Beit, zur Naturges. der Clad., p. 27. 



? Leydigia quadrangularis, Kurz, Dodekas Neuer Cladoceren. 

 1884. Leydigia quadrangularis, Herrick, loc. cit., p. 88, pi. H, fig. 4. 



This species is easily identified by the remarkably broad and almost 

 semicircular post-abdomen. Norman and Brady include Alona leydigii, 

 Schcedler, with Lynceus acanthocercoides, Fischer, and reproduce Fischer's 

 figures of the species. These figures do not agree with Herrick's figure of 

 post-abdomen of Leydigia quadrangularis, whereas the Lochgelly specimens 

 agree perfectly with Herrick's description and figure. I have followed 

 Herrick in adopting Kurz's name for this Lynceid. 



Lynceus, Muller. 



Lynceus tenuicaudis (G. 0. Sars). 



1862. Alona tenuicaudis, G. 0. Sars, op. cit., Andet Bidrag., p. 37. 

 1867. Lynceus tenuicaudis, Nor. and Brady, loc. cit., p, 376, pi. xix. fig. 3. 

 1884. Alona tenuicaudis, Herrick, loc. cit., p. 95, pi. i. fig. 2. 



This species is easily recognised by the form and armature of the post- 

 abdomen, which is long, with the sides nearly parallel, " incised below, 

 lower angle armed with about six strong teeth, the remainder of the series 

 small." 



