240 MISS A. L. EMBLETON ON THE ANATOMY 



Tracheal system — The main trachese run in two lines parallel with the sides of the 

 body ; being full of air, they can be seen plainly through the semitransparent body- 

 walls ; anteriorly they are connected by a transverse commissure in the second segment 

 behind the head ; there is also a posterior connection. 



Bugnion (9) states that there are nine pairs of stigmata in the larva of Encyrtws fusri- 

 collis, occurring in the segments two to ten. Reinliard (47) has counted the same 

 number in Fteromal'mcB larvae {Decatoma, CalUmone, Eupehnus, Pteromalus). Laboul- 

 bene (35) describes also nine in the larva of Pimpla Favrmairei; but Ratzeburg (46), in 

 the larva of Anomalon circumflexwn, a parasite of Bombyx, found no stigmata at all, 

 which he says is due to the fact that the larva lives inside the caterpillar. In the larva 

 of Comys infelix at this stage I have been unable to detect any stigmata, though I have 

 employed many methods in preparing the larvae for the microscope, hut always with 

 negative results. Possibly the tail-apparatus takes the place of stigmata, for it is a most 

 remarkable arrangement, and suggests a parallel with the metapneustic tracheal systems 

 of some Dipterous lai'vse in which there exist only a terminal pair of spiracles. In some 

 metapneustic Dipterous larvae a pair of anterior spiracles appear later ; this is then 

 called an amphipneustic larva. The arrangement in which the normal stigmata are 

 present is called peripneustic. 



Alimentary system. — In the bluntly rounded anterior end there is a circular mouth 

 with a soft rim or lip (PI. 11. fig. 11) ; inside there are two chitinous mandibles, each 

 being a simple tooth or claw, one of which overlaps the other ; these mandibles possess 

 a powerful muscular apparatus. Prom the mouth, the alimentary canal runs to the tail ; 

 immediately behind the mouth there is a funnel-shaped pharynx, leading through an 

 cesophagus to the stomach, in about the third segment. On either side of the stomach 

 is a gland, probably possessing a salivary function (PI. 11. fig. 13) ; these glands open 

 into the pharynx. The alimentary tract is straight, apart from the stomach, which is 

 sac-like and fills the larger part of the body-cavity, and contains fat-globules and other 

 dark-coloured granules ; it looks darker than the rest of the body, which is white, and, 

 under a high power of the microscope, is seen to be granular. There is a short intestine 

 behind the stomach, but at this stage it is not connected with the anus. 



ii. Second Stage. 



External form,. — The body now measures 1-75 mm. As the two-tailed larva grows its 

 contents get more and more aggregated into ball-like masses. The body becomes rounder 

 and thicker, while the tails atrophy (PI. 11. fig. 13), till the stage is reached (fig. 14) in 

 w hich the posterior end is rounded, but the two tracheal trunks are still visible projecting 

 out of the body as withered ends not yet quite cast off. 



Tracheal system. — Apart from the difference in the tail-apparatus, the two main 

 trachege remain unaltered except for the fact that in each segment they give off a 

 group of secondary branches. In this stage I have found the anterior and posterior 

 commissures still present ; in front of the anterior connective the main trunks continue, 

 ultimately ramifying in the head ; behind the posterior commissure the trunks are 



