Miscellaneous. 317 



with a dark, longitudinal streak down the back, which is the dorsal 

 vessel. They are long and slender (fig. h represents a group of four 

 of them of the natural size, and fig. c one of them highly magnified). 

 The body consists of thirteen segments, gradually but slightly 

 tapering towards the head, the segments being armed at the sides 

 with strong bristles. They are destitute of legs, but are nevertheless 

 able to crawl along with great rapidity, using the parts of the mouth 

 and the appendages at the end of the body in locomotion. When 

 disturbed they writhe about in a serpentine direction, or coil themselves 

 up spirally remaining for a short time immoveable, and thus easily 

 escape observation. The head is small and conical, furnished with 

 two short antennae composed apparently of two joints, the basal one 

 being very short, and the outer one terminated by a bristle (fig. d re- 

 presents the front of the head seen from above, very highly magni- 

 fied) ; the mouth is furnished with two large brown horny jaws, point- 

 ed in a slight hook at the tips (fig. d**), and the lower part of the 

 mouth seems to consist of a large fleshy somewhat bilobed lip, furnished 

 with two very minute two-jointed palpi. I also observed a small 

 semi-globular tubercle on each side of the head behind the antennae, 

 which may be the rudimental eyes. The terminal segment of the 

 bodj'^ is furnished with two small deflexed hooks, preceded by a co- 

 ronet of minute setae, and which are evidently employed in walking. 



When full-grown these larvae assume the pupa state, having first 

 entirely voided the remains of their undigested food, as is the custom 

 with other larvae. All the larvae which I kept encased themselves 

 within a cocoon of a silk}^ texture and of an ellipsoid form, of a 

 whitish colour within and grayish externally, often covered with 

 minute particles of the adjacent materials Rosel, however, observed 

 that some of the larvae underwent these changes without forming a 

 cocoon. The pupa inclosed within the cocoon bears considerable 

 resemblance to the perfect insect, with this difference, that the legs 

 are folded close on the sides of the body, and the insect is inclosed 

 within a thin pellicle, each of the limbs being covered by a distinct 

 case ; of course during this period the insect remains quite inactive, 

 but as soon as the period for its final transformation arrives, it 

 stretches forth its limbs, and casts oflF the thin pellicle with which 

 it had been covered, and then appears as a perfect flea. Figure e 

 represents the pupa highly magnified, with the cast skin of the larva 

 (fig. /) attached to the extremity of its body. 



