56 Proceedings of the Royal Society of Edinburgh. [Sess. 
apical black fceeth pointing forwards, the femoral joint bearing besides a 
second tooth on its inner edge. 
Prelabial region (tig. 3) with the usual strongly chitinised acute angles, 
without any distinct paler area, but with a transverse row of 4 + 4 short 
setae. Lateral labial plates with their posterior internal angles overlapping- 
each other, the oblique median ridge thick and dark, and the posterior 
edge thin (not darkened) and destitute of setae or lashes. Median plate 
oval, partly concealed behind, exposed towards the front. Mandibula with 
a dentate (6 to 7-toothed) lamella and seven pectinate lamellae; the latter 
formed of 14, 14, 14, 14, 11, 10, and 4 distinct, blunt teeth. Coxosternum of 
first maxillae divided, with but few setae. Coxosternum of second maxillae 
(fig. 2) long and narrow, deeply 
excised anteriorly ; the structureless 
lateral (coxal) regions comparatively 
less developed than the posterior 
(sternal) reticulate region. Setae more 
numerous in the middle; two strong 
setae along the inner margin of each 
of the coxal regions. 
First tergite with two wide and 
shallow, longitudinal impressions ; the 
other tergites smooth, bisulcate from 
the second to the penultimate. Ster- 
nites smooth ; the 2nd to about 
the 23rd with a distinct median 
sulcus, the anterior end of which is 
divided into two short branches, which diverge more and more so as to 
soon become almost horizontal, the median sulcus growing longer. 
Towards the 24th segment the sulcus is rather suddenly replaced b}^ 
a longitudinal shallow impression, more or less distinct on the following 
sternites. Last segment elongate. Last tergite not quite twice as 
long as the penultimate, parallel-sided, rounded backwards. Sternite 
short, not exceeding half the length of the adjoining coxae of the anal 
legs, heart-shaped, poorly strewn with short setae. Coxae of anal legs 
long and slender ; pores moderately numerous (some 25 to be seen on the 
ventral surface and perhaps 10 more dorsally). Anal legs wanting. 
Male unknown. A single female collected at “ Amara on Tigris, — vii. 
1918." 
The only two species of Mecistocephalus known to possess 51 pairs of 
legs are M. lifuensis, Pocock, from the Loyalties (Lifu), and M. erythroceps, 
Fia. 3 . — Mecistocephalus Evansi, n. sj) 
Labral region, ventral view. 
