[30 



ones between tliem ; the twelfth is similar to but smaller tlum the eleventh, and 

 with only short bristles ; the thirteenth is immediately behind this and close to- 

 the extremity of the body ; it consists of a rounded subtriangular piece, with 

 its outer rounded extremities curled round so as nearly to meet, and a sepa- 

 rate narrow piece at its posterior margin ; from within the curled edges there 

 proceed backwards two transparent processes, each with a disk-shaped ex- 

 tremity. 



The dorsal plates are situate in the sulci, between the segments, the ven- 

 tral ones about the middle of each segment. All these plates are of a deli- 

 cately tessellated structure, as if constructed of flattened cells arranged in arches 

 springing from their posterior margins (Fig. H. third dorsal plate) ; the femora 

 have a similar structure, and, in a prepared specimen, I see that their dorsal 

 margin is toothed where the differeint cells overlap each other. 



These plates may be regarded as a beautiful display of the dermal anatomy 

 of the little active larva ; and the above description is doubtless equally ap- 

 plicable to it. In examining the little black mite-like larva I did not notice 

 any setae, except a short one at the side of each segment ; these were probably 

 those of the secondary dorsal plates. As a parallel instance of the separation 

 of the chitinous plates of the dermal skeleton, I may refer to the case of the 

 female of the white ant, as described by Smeathman, where he mentions the 

 PuJex penetrans as the only similar instance known to him. I found more 

 than a dozen of these larva? within full-grown wasp-larvre, and had the plea- 

 sure of watching three of them emerge from the wasp-grab. The usual, and, 

 I believe, the only normal place to emerge is at the anterior aspect of the 

 fourth segment (head = 1st). The Rhipiphorus, which is usually in motion, 

 and for its situation might be called tolerably active, is seen to lay hold of the 

 interior of the skin with its anterior legs, and keeps biting and scratching 

 with its strong and sharp jaws until it is able to thrust through its head, 

 when, in less than a quarter of an hour, it completely emerges by a vermiform 

 movement ; and at the same time it casts a skin, together wtih the black head, 

 legs, plates, ko. Its anterior surface as it emerges is directed towards the head 

 of the wasp, and, bending forwards as it emerges, and guided probably when in 

 its natural position by the wall of the cell, it passes forwards as it emerges 

 along the anterior surface of the wasp-grub, until its head comes somewhere 

 near the second segment of the wasp on its dorsal or lateral aspect, where it 

 at once seizes hold (Figs. 3 and 4). When removed from the cell, as those I 

 examined were, the first few segments of the Hhipiphorus came directly out- 

 wards, though they equally succeeded in seizing the wasp-grub by the shoul- 

 der. The place of emergence is marked by a slight puckering, and by the 

 black particles of the cast skin. There seems to be no escape of fluid from the 

 wound thus made : for one thing, it is smaller than the diameter of the Rhi- 

 jiiphorus-laxvA,, which squeezes through it and plugs it for the time ; and after- 

 wards it is to a certain extent stopped by the cast skin of the Rhipiphorus. 



