102 MONOGRAPHIA CHALCIDITUM. 



animal. If we attentively examine the fore-foot, we shall per- 

 ceive on each side immediately below the knee, a transparent 

 protuberance, coloured in some species and white in others, 

 covering a cavity in which the extremity of the tube terminates. 

 This transparent plate presents an analogy to that part in the 

 crickets to which I have given the name of mirror. This pro- 

 thoracic cavity is found in both sexes : the larvae and pupae 

 possess it: hence we may infer this organ is useful to the 

 insect in all the stages of its existence. But what its functions 

 are, I do not know. We cannot consider it a stigma, since it 

 has no communication with the trachese ; it remains constantly 

 open, and does not appear to be under the animal's control, 

 which is not the case with the other thoracic stigmata, which 

 are formed of two moveable lids resembling eyes with the eye- 

 balls removed. In order to satisfy myself that this cavity was 

 not the opening of a stigma, I plunged a grasshopper head- 

 foremost into water, and held it there till it was drowned. The 

 cavity remained motionless, and did not appear affected by the 

 contact of the liquid, whilst bubbles were seen at the orifices 

 of the four thoracic stigmata. This experiment, repeated many 

 times and always with the same results, leads me to conclude 

 the great prothoracic cavity is not a respiratory opening ; and 

 what makes the correctness of this conjecture more probable, is 

 the possibility of removing the part in question, together with 

 its tube, from the insect without injury. 



To he conl'inued. 



Art. XII. — Monographia Chalciditum. By Francis 

 Walker. 



(Continued from page 55. J 



the green myriads in tlic peopled grass." 



Genus Encyrtus — continued. 



Fern. — Corpus breve, crassum, convexum, punctatum, parum nitens: 

 caput transversum, breve, juxta thoraci latum ; frons abrupte 

 declivis : antennae clavatae, pubescentes, corporis dimidii longi- 

 tudine; articulus 1". fusiformis, dilatatus; 2"Mongi-cyathiformis ; 



