Anatomy &c. of the Colies. 235 
The Pterylosis of some other Species of Colius compared 
with that of C. affinis. 
The differences in the matter cf pterylosis between 
C. affinis and C. striatus, C. capensis, C. castanotus, and 
C. erythromelon appear to be very small, and are confined 
almost entirely to the pt. capitis. 
C. striatus (text-fig. 12).—The parietal apterion of this 
species differs from that of the other species herein described 
in that it is larger and has assumed an oval shape, laterally 
passing, as before, into the ocular area; while from the 
anterior margin of this area there runs backwards a horse- 
shoe-shaped loop. 
Text-fig. 12. 
fo) 
Dorsal aspect of the head of Colius striatus, shewing the 
parietal apterion, 
apt.cap.=apterion capitis. 
C. erythromelon (text-fig. 18, p. 236).—The pt. capitis 
differs conspicuously from that of P. affinis (text-fig. 10, 
p. 231) in the great size of the parietal apterion and the 
larger size of the ocular area, which runs into the parietal 
area on either side. The parietal apterion takes the form 
of a broad T-shaped space, the limbs thereof narrowing 
immediately above the anricular aperture and passing in- 
sensibly into the ocular area. The anterior boundary of 
the space does not extend beyond the level of the posterior 
border of the orbit ; while the median stem of the “T”’ rans 
downwards to the occiput, tapering slightly to its base, 
