AKT. 17, MONOPHLEBINAE AND MARGARODINAE—MORRISON. 37 
thoracic and seven pairs of abdominal spiracles, the first of different 
construction, but only slightly larger than the abdominal pairs, all 
with pore collar, at opening in thoracic, set well in from opening in 
abdominal spiracles;® derm pores of one type only, relatively very 
large, circular, flat disk pores with large clear centers, apparently 
slightly granular, and marginal circles of numerous (about 30) small 
loculi, the outer ring with a slight internal swelling at one point, and 
an additional still smaller pore in this; derm setae all small, stiff, 
rather stout, set in a flat circular collar, not numerous, scattered, less 
abundant than the pores, but, like these, in greater number along 
the body margin; anal tube small, short, simple; ventral cicatrices all 
small, some little larger than the pores, in transverse rows of well- 
gi 
Fig. 17.—PLATYCOELOSTOMA COMPRESSA (MASKELL). LARVA. A, DORSAL AND VENTRAL, X5/7.5; 
B, claw, X640; C, seta, 500; D, THORACIC SPIRACLE, X1,500; E, DISK PORE, X1,500; F, 
DISK PORE, X1,500; G, ANTENNA, 57.5; H, LEG, 220. 
separated cicatrices on the abdomen at least, the ends of each row 
with a cluster of larger ones. 
Larva.—Elongate, posterior apex rounded, anterior somewhat 
pointed; length 1.115 mm. width .45 mm.; antennae short, distinctly 
7-segmented, the intermediate segments very short; legs short, widely 
separated, tarsal claw with denticle and slender, slightly knobbed 
digitules extending beyond the apex of the cluw; beak long and 
9In one of the Maskell slides of this stage, in which the trachneal system has been preserved toa large 
extent, there may be seen quite plainly an eighth pair of abdominal spiracles, about half the size of the 
others, and without the pore collar, but with the usual band of small internal hairs. Neither these nor 
their external openings have been definitely located in any of the other intermediate stage females 
examined (three). This condition suggests the beginning of a process of suppression in the abdominal 
spiracles commencing with the apical pair. 
