84 ON THE SYNONYMY OF THE PERLITES. 



RhamphastidcB by Mr. Swainson, solely on account of the 

 magnitude of its bill ; the actual structure of which, however, 

 together with every detail of conformation, even to that of an 

 individual feather, also the style of colouring, the progressive 

 changes of plumage, and indeed everything that can be sup- 

 posed to indicate real affinity, combining to show the impro- 

 priety of such arrangement, and alike intimating the close and 

 immediate relationship of that genus for the restricted cuckoos, 

 with which it even forms a particular subdivision of the fa- 

 mily Cuculidce, peculiar to the eastern hemisphere. 

 (To be continued). 



Art. VI. — On the Synonymy of the Perlites, together with brief 

 Characters of the old, and of a few new Species. By Edward 



Newman, Esq., F.L.S. ' 



(Concluded from Page 37). 



Genus IV. — Isogenus, Newman. 



The genus was separated from Perla on account of its hav- 

 ing the wings equally developed in both sexes. The habit 

 is also more slender, the wings more ample. They have usu- 

 ally fifteen nervures, reaching the margin of the fore-wing be- 

 tween the subcostal nervure and the base, 



Sp. 1. Isog. Ligea. Fusca: facies testacea ; abdomen testaceum, later- 

 ibus saturatiorihus; alae vix hyalinae, croceo-brunneo tinctae. (Corp. 

 long. .55 unc. alar, dilat. 1.5 unc.) 

 The face is testaceous, the other parts of the head, and the entire pro- 

 meso- and meta-thorax are dark brown and glabrous ; the abdomen is dor- 

 sally testaceous, laterally dusky brown : the wings are scarcely hyaline, and 

 are tinted throughout with a clear, rich brown, resembling the colour of 

 burnt sienna. 



The country of this species is unknown. A single speci- 

 men is in the cabinet of the Rev. F. W. Hope. 



Sp. 2. Isog. nubecula. (Corp. long. .6 unc. alar, dilat. 1 .5 unc.) 



„ „ Newman; 'Entom. Magazine,' vol. i. p. 415. 



„ „ Stephens, * Illustrations of British Entomology,' 



Mand. vol. vi. p. 137, tab. xxxi./^. 2. 



The text refers to tab. xxxi.^t/. 4, which represents Leuc- 

 tra geniculata, Steph., subsequently also erroneously referred 

 to fig. 3, which represents Nemoura rariegata, Steph. — 

 The figure of Isog. nubecula is without the brown spot on the 

 forewing, which serves most readily and obviously to distin- 

 guish this species from those which follow. 



