12 MONOGRAPHIA CHALCIDUM. 



accordance with the medium in which they reside. For 

 example — the greater part of the Decapoda Macroura are in 

 no respect adapted for swimming ; and amongst the Isopoda, 

 the Ligise, which are marine, and the Onisci, which are terres- 

 trial, present no sensible difference of structure. The Hy- 

 drachnae, also, offer no character which indicates their aquatic 

 habits. — (To be continued.) 



Art. II. — Monographin Chalcidam. By Francis Walker, 

 Esq. F. L.S. 



In the variety of their forms, the brilliancy of their colours, 

 and probably the number of their species, the Chalcides excel 

 every other family of insects. Very few have been described, 

 except the species of Encyrtus, by Dalman, to whom, and 

 Spinola, we owe the little information we possess. They may 

 be divided into two primary groups, to which the names 

 Pentameri and Tetrameri are applicable, from their five or 

 four-jointed tarsi. The tetramerous tarsi have been noticed by 

 Mr. Curtis in describing the genus Eulophus : the species of 

 this division are usually smaller than the Pentameri ; their 

 bodies are softer ; their colour less generally metallic ; they 

 run faster, but do not leap so far. 



Section 1. — Chalcides Pentameri. 



Tarsis quinque-articulatis. 



Family I. — Eurytomid.e. 



Type, — Eurytoma. Illiger. 



Caput transversum : oculi laterales : ocelli in triangulum dispositi : 

 maris antemiae 11-articulatse, setaceae, filiformes aut clavatag : 

 femincs antennae 12-articulatae, clavatse : mandibulse apice angus- 

 tiores, tridentatas : maxillee elongatae : mentum elongatum, quad- 

 ranguhim : labium basi angustum, antice sinuatum : palpi 

 maxillares articulis 3 aut 4 : pcalpi labiales biarticulati : thorax 

 gibbus aut cylindricus : prothoracis* scutelluni magnum, sub- 

 quadratum : mesothoracis scutellum bene determinatum suturis 

 duabus lateralibus, scutum convexuni ovatum, paraptera tri- 

 angula: metathoracis pra^scutum angustum, scutellum magnum 



» In describing the parts of the thorax, 1 have adopted Mr. MacLeay's nomen- 

 clature. 



