138 Mr. G. R. Waterhouse on two new genera of 



contracted before and behind ; the posterior angles acute, the anterior 

 angles slightly rounded ; dorsal channel distinct, and extending from 

 the anterior to the posterior margins ; on the disc of the thorax this 

 channel is very broad ; a transverse depression is observable on the 

 hinder part of the thorax, and the space between this depression and 

 the posterior margin is thickly but finely punctured ; the lateral 

 margins are reflected, and present a few scattered punctures. The 

 elytra are ovate, but little convex, and obtusely rounded at the apex ; 

 punctate-striated, the punctures small, and the spaces between the 

 striae slightly convex ; the lateral margins of the elytra are reflected. 

 The colouring of the upper parts is blackish green ; the under par-t- 

 are pitchy ; the thighs are also pitchy, but inclining to reddish ; the 

 tibiae and tarsi are black ; the antenna; have the four basal joints of a 

 pitchy red colour, and the remaining joints dusky ; the palpi are 

 also pitchy red, but the terminal joint is blackish in the middle. 



This species approaches in form the M. ovalis, but differs in being 

 more depressed, and in having the apex of the elytra obtusely 

 rounded. 



Migadops Darwinii. — Mig. ater, antennis ad basin, pedibusque 

 piceo-rubris, corpore subtus piceo ; thorace postice punctulato, 

 transversim impresso, et foveis duabus magnis notato ; elytris 

 punctato-striatis. Long. corp. 3 \ lin. ; lat. 1 J lin. 



Hob. Tierra del Fuego. 

 Head broad, depressed, and with four shallow fovea? arranged in 

 a transverse line between the eyes : thorax broader than long, di- 

 lated in the middle and contracted behind ; the upper surface but 

 little convex ; the dorsal channel short, the sides rather broadly mar- 

 ginated, especially towards the hinder angles, where the lateral mar- 

 gin is recurved ; behind is a faint transverse impression, and two 

 large shallow foveas ; these, as well as the whole space between the 

 transverse impression and the posterior margin, are rather thickly 

 and finely punctured ; some punctures are also observable on the 

 lateral margins, which have a pitchy tint : elytra considerably broader 

 than the thorax, and of a short ovate form, moderately convex above, 

 and punctato- striated ; the punctures are small, and arranged closely 

 together ; the interspaces of the striae are nearly flat. The general 

 colour of the insect is black, and it is moderately glossy ; the palpi 

 and four basal joints of the antennae are pitchy red, but the terminal 

 joint of the former is blackish in the middle, and so is the apical 

 portion of the second, third and fourth joints of the antennae ; the 

 body beneath is pitchy red, and so are the legs. 



The pitchy tint of the under parts of the present insect would 

 lead one to suppose the specimens to be somewhat immature. 



Mr. Darwin found this insect at Navarin Island, near Hardy 

 Peninsula ; its form differs but little from the Mig. ovalis (PI. III. fig. 

 3); the body, however, is broader, the thorax is more broadly margi- 

 nated, and the lateral margins are more recurved near the posterior 

 angles. In size the present species slightly exceeds the M. ovalis. 



Migadops nigro-caruleus. — Mig. nigro-caeruleus ; corpore subtus, an- 

 tennis, pedibusque piceo-nigris ; thorace postice transversim im- 

 presso, punctis minutissimis adspersis, foveisque duabus ; elytris 



