•UO Mr. W. C^ Crawley on 



The following table, giving the comparative dimensions 

 of tlie iieads of these five forms, shows at a glance liow they 

 are related (that of coriarius is taken from an example 

 kindly given me by Emery, and came from the GodcHroy 

 Museum) : — 



septentrionnlis, 



rujiceps, ty}^e, co-type. (Fig. 4.) conan'iis. \iir.oliscura. 



Loncrth 37 mm. 39 mm. 3-3 mm. 3-4 mm. 



Width at eves 2-8 „ 27 „ 2-5 „ 2-r» „ 



AVidth at occiput . 2-1 „ 20 „ 2-0 „ 20 „ 



cephalotes, Sm., 

 actitideyis. (Fig-. 5.) type. (Fig. 6.) 



Length ^ major 33 mm. § minor 22 mm. 3-3 mm. 



NVidthateyes.... „ 27 „ „ 17 „ 25 „ 



Width at occiput . „ 21 „ „ 12 „ 1-9 „ 



Fig. 4. Fig. 6. Fig. (5. 



Fig. 4. — Mandible of O. septentiionalis, Craw. 



Fig. 5. — Mandible of O. acutidens, For. 



Fig. 6. — Maudible of O. cephalotes, Sm., type. 



It will be seen from the above measurements that rnficeps 

 and septentrionaVis approximate very closely in the shape of 

 the head, that of septentrioncdis being very slightly longer 

 and narrower. In fact, the only ditiereuee 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. ohscura are almost identical. 



O. coriarius, therefore, should rank as a species distinct 

 from ruficeps, while septtntrionalis 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 $ , and should 

 rank as a distinct species. 



Emery has seen the var. obsctira and septentrionalis, and 

 agrees with me that ruficeps must be considered as a species 

 distinct from coriarius^ cephalotes, ajax, and acutidens. 



