Séance du 24 Décembre 1924 377 
the base; uniformly tapering, about half as wide at 
the tip as at the base; bristles on the valves large, 
strongly curved. Hair tufts in a single ventral row 
of 16 to 19 long tufts, running almost the whole length 
of the siphon, the longest near the base, where they 
are nearly two-thirds the length of the siphon, their 
length decreases rapidly towards the apex of the si¬ 
phon. 
There are usually two minute lateral tufts of two 
or three very small hairs rather beyond half-way. 
Pecten teeth usually 9 or 10, sometimes 8, the basal 
3 or 4 small, and the apical one slightly detached 
from the remainder, with three or four rather short 
denticles, the basal two of which are usually close 
together and detached from the upper one. Saddle of 
anal segment with the dorsal edge nearly twice as 
long as the ventral, entirely covered with very mi¬ 
nute hairs. Dorsal tuft of a single long hair plus a 
tuft of one long and strong, and two shorter and 
weaker hairs on each side, the longest hair longer 
than the siphon. Ventral brush abundant, three or 
four small tufts anteriorly, but at most one outside 
the barred area. Anal gills long, pointed, rather lon¬ 
ger than the width of the saddle. 
This interesting species has been taken in two 
widely separated localities in the Eastern Desert, both 
during April, 1924. The larvae were first found in se¬ 
veral rock pools in the Wadi No’oth, in the North 
Galala Mountains, at an altitude of about 35 o metres. 
A few days later they were also collected by Mr. N. D. 
Simpson, at an altitude of 800 metres, higher up the 
same wadi. Towards the end of April I also found it 
