EXTERNAL PARASITES OF SPIDERS. 171 



white spider's web, on a dry oak-leaf, three satiny white, dipterous- 

 looking larvae, and the dead spider (Cluhiona holosericea, Linne). 

 He suggests that the larvas had fed on the eggs of the Cluhiona, 

 doubting whether there was sufficient of the Drassid to nourish 

 the three larvae. Laboulbene refers to the blackish cloud in the 

 interior of the body of the larva, which "he did not believe" was 

 an internal parasitic larva, but only the alimentary canal ; and 

 remarks that, after much hesitation, he was convinced that the 

 feet (pseudopodes) were not upon the ventral, but upon the dorsal 

 surface of the larva. One of these larvae was killed in exami- 

 nation, but the other two spun oblong cocoons of thin white silk, 

 and in about a fortnight two female Ichneumons emerged (Ann. 

 Soc. Ent. France, 3rd ser., vol. vi., p. 798, pi. 17). Dr. Laboul- 

 bene's detailed description of the larva is as follows :— 



"Larva elongate, slightly curved (figs. 1-3), composed of 

 thirteen segments, counting the terminal tubercle (mamelon), but 

 not the head. Whitish grey in colour, slightly shining, satiny. 

 The dark alimentary canal shows plainly in its interior (fig. 2), 

 and numerous whitish granulations are observable under the 

 skin. Long 7 mm. 



"The ventral region is concave, smooth, apod; the sides of 

 the body are sharply rounded ; but the most important point in 

 the structure of this larva is the existence of ' pseudopodes ' or 

 false legs situated in the centre of the dorsal or convex region, 

 and to which I shall again refer. Head small, a curvilineal 

 triangle, brownish, appearing to be furnished with two small 

 biarticulate antenn&e (fig. 5 ft), with a rounded, ciliated labrum, 

 and with two mandibles. The parts of the mouth are not easy to 

 distinguish. Thoracical segments largest of all, and rounded 

 laterally and dorsally. Abdominal segments tuberculate ? (ma- 

 melonnes ?) on the sides, the 1st to 7th having in the middle of 

 its back true retractile 'pseudopodes' similar to the false legs of 

 caterpillars, having like them a crown of hooks, which holds them 

 firmly in an}' position. The two terminal segments (8th and 9th) 

 are trapezoid, forming, with the anal appendage, an inverted cone. 

 There are nine pairs of spiracles ; the first situated on the 

 anterior margin of the metathorax ; the second upon the 1st 

 abdominal segment (4th of the body of the larva) ; the third, 

 fourth, fifth, sixth, seventh, eighth, and ninth spiracles upon the 

 2nd to 8th abdominal segments. A long central trachea traverses 

 the body, emitting a branch to each spiracle ; fig. 2 shows their 



