488 Mr, Gilbert J. Arrow on Characters and Relationships 



yet been described. Like the female it has head, pro- 

 thorax and legs of a bright yellow colour and the elytra 

 usually a little duller, but the claws have in the male 

 a strong tooth near the middle, the labrum is larger, 

 and the mandibles are broad and prominent, almost as 

 in the males of Phacochrous. The front tibiae and tarsi 

 are longer, and the tibiae have only two teeth instead of 

 three. A very curious feature is the contraction of the 

 hind tarsi, which are very short and thick. Finally, 

 the hind tibiae bear at the end a tuft of very long hairs 

 which actually extend beyond the tarsi. This curious 

 genus is almost the only Lamellicorn genus which is 

 apparently peculiar to the West Indian Islands. 



The most salient characters of the Hijhosorinae are 

 frequently peculiar to the male, a fact unknown to West- 

 wood, who relied chiefly upon these features in his synopsis 

 of the genera (Trans. Ent. Soc. Lond., IV, 1847, p. 157). 

 This is therefore useless and liable to mislead unless the 

 sexual differences of the species under examination are 

 known. As several recently described genera are yet un- 

 known to me I cannot at present replace it with a fresh 

 tabulation of the now much more numerous genera. 



The geims PJiacochridius consists of the two species 

 P. derasus, Har., and P. Haroldi, Fairm., and the only 

 character which has been mentioned as distinguishing it 

 from Phacochroops is the existence of a transverse carina 

 on the posterior tibiae. This is found in quite typical 

 species of Phacochroops and therefore has no generic value ; 

 but there is a considerable difference in the shape of the 

 pronotum, which is more or less quadrate in Phacochroops, 

 while in Phacochridius there is no trace of hind angles, the 

 margin forming a continuous curve from one front angle to 

 the other. To this distinction may be added a peculiar 

 sexual feature. In the female the puncturation of the 

 elytra is interrupted on each side behind the scutellum, 

 leaving a very conspicuous shining patch. I have found 

 this constant in a considerable series of P. Haroldi from 

 Batu I. in the Genoa Museum, and have ascertained by 

 dissection that it is distinctive of the female sex. Harold 

 described the same peculiarity as occurring in P. derasus, 

 so that the type of that species is a female. 



Hypselodcrus, of Fairmaire, from the description is 

 evidently not a member of the Hyhosorinae. It probably 

 belongs to the Troginae. 



