440 Mr. W. C. Crawley on 
The following table, giving the comparative dimensions 
of the heads of these five forms, shows at a glance how they 
are related (that of coriarius is taken from an example 
kindly given me by Emery, and came from the Godeffroy 
Museum) :— 
septentrionalis, 
ruficeps, type. co-type. (Fig.4.) coriarius. var. obscura. 
Hen eth ec sx wes 37 mm. 3°9 mm. 3o'3 mm, 3-4 mm. 
Width at eyes.... 2°8 ,, Dahan, 2b" =f 2 Dee. 
Width at occiput. 2:1 ,, 2:00 209, 20 
cephalotes,Sm., 
acutidens. (Tig. 5.) type. (Fig. 6.) 
Weng thie ty-sicss $ major3°3 mm. 8 minor2?:2mm. 38:3 mm. 
Width at eyes.... a Des i eet 2D 55 
Width at occiput . Se ee Pr tn Por Oar 
Fig. 4, Fig. 5. Fig. 6. 
Vig. 4.—Mandible of O. septentrionalis, Craw. 
Fig. 5.—Mandible of O. acutidens, For. 
Fig. 6.-Mandible of O. cephalotes, Sm., type. 
It will be seen from the above measurements that ruficeps 
and septentrionalis approximate very closely in the shape of 
the head, that of septentrionalis being very slightly longer 
and narrower. In fact, the only diiference between the two 
forms, apart from this, lies in the shape of the mandibular 
teeth. ‘The dimensions of the heads of coriarius and its 
var. obscura are almost identical. 
O. coriarius, therefore, should rank as a species distinct 
from ruficeps, while septentrionalis can only be considered a 
var. of ruficeps. On the other hand, acutidens differs from 
the others in having a shorter and proportionately broader 
head, and also in possessing two forms of 8, and should 
rank as a distinct species. 
Emery has seen the var. obscura and septentrionalis, and 
agrees with me that ruficeps must be considered as a species 
distinet from coriarius, cephalotes, ajax, and acutidens. 
—" 
