28 THE CANADIAN ENTOMOLOGIST. 



sides of the body. There are at least tsvo pairs of minute dorsal spines. 

 One pair is situated one on each side of the third abdominal segment; 

 another pair is situated one on each side of and anterior to the operculum. 

 Each of these four spines arises from a minute papilla, which, however, in 

 certain lights, appear like cylindrical cavities or pores. From a study of 

 later instars, it seems possible that another still more minute pair of s})ines 

 occurs on the cephalic region, but I have not thus far distinguished any 

 such with certainty. The two pairs above located are not difficult to see 

 with a one-sixth inch objective. 



On the ventral side of the body the legs, antennae and mouth-parts 

 are well developed in this instar. Each leg (Fig. 3) consists of a coxa, 

 trochanter, femur, tibia and tarsus. The entire length of the leg when 

 straightened is about one-half the width of the body. The coxse are short 

 and stout, and near the base of each of the two posterior pairs on the 

 inner side is a spine about twice as long as the diameter of the coxse. 

 Trochanters short, those of the anterior pair of legs are subcylindrical, 

 about one-third as long as wide. Those of the two posterior pairs of legs 

 appear to be hoof-shaped, and all six trochanters bear a short spine 

 anteriorly. The femur is about twice as long as the coxa and trochanter 

 together, subcylindrical in form, tapering toward its outer end. The 

 tibia is a little longer than the femur, and more slender; in the two 

 posterior pairs of legs, bearing on its outer side, near its base, a spine as 

 long as the whole tibia itself. This extends obliquely outward, and 

 is usually curved near its tip. Under high-power objectives and with 

 favourable light the tibiae are seen to bear a number of very minute spines. 

 The tarsus is short and knobbed at the tip, with a stoat curved spine one- 

 half as long as that borne on the tibia, arising on the outer side near its 

 base. Diagonal lines connecting the two anterior pairs of coxte would 

 intersect at about the centre of the base of a conical papilla— the rostrum 

 — from an opening in the apex of which the mouth setse protrude. The 

 length of these setae varies, but when bent backward they usually extend 

 beyond the hind coxae. In front of these mouth organs is a prostomial 

 plate or shield, subovate in form, the broader end being anterior. It is 

 truncate where it touches the base of the mouth papilla, slightly concave 

 on the sides posteriorly, broadly rounded anteriorly, with two movable 

 papillae on the anterior margin, each of which bears a long spine, about 

 equal in length to those on the coxje of the two posterior pairs of 

 legs. From the anterior two-thirds of this plate are separated two 



