1,'iO NORTHERN ZOOLOGY. 



Body between oblong and obovatc, not hairy. Head inserted, subtriangular with the vertex of 

 the triangle truncated ; rhinarium transverse, vertical, widely emarginate ; nose transverse, distinct, 

 anterior margin reflexed and subemarginate ; no distinct postnasas or afternose ; canthus septiform, 

 cleaving: 7 prothorax transverse with an interior sinus of its whole width to receive the head : scutellum 

 short, triangular, somewhat rounded at the vertex : podex and part of the penultimate dorsal segment 

 of the abdomen uncovered: legs thus located :: ; cubit tridentate ; tarsi filiform, slender: claws 

 bipartite, the interior lobe the shortest and widest, and very obtuse ; the exterior very slender and 

 acute. 



This genus, at the first blush, seems to exhibit some affinity both with Chalepus and Apogonia ; 

 with regard to the latter, this arises merely from its having few or no hairs, and from its rows or punc- 

 tures in pairs observable in the elytra ; but with the former it agrees in more particulars, for its 

 mandibles are truncated at the apex and concavo-concave, as those of Chalepus are represented, and 

 correctly, in Mr. Mac Leay's figure ; g the antenna; likewise are not very different, except that the 

 scape in the latter insect is more dilated at the apex : but this exhibits a character which at once 

 separates it, and widely, from Diplotaxis, the prosternum sends up a vertical process behind the 

 base of the arms, hairy at its summit, a character which is to be detected, but more or less conspi- 

 cuously, in all the various genera and subgenera that form Mr. Mac Leay's large family of Dynas- 

 tidce though it is less prominent in Megasoma, the most gigantic genus of them all. The maxilla?, 

 often so constant, in this family or rather tribe, vary without end, the mandibles arc more constant, 

 as is also the labium, but the vertical prosternum, 9 varying as to elevation and shape, is their constant 

 diagnostic: so that it is evident that Chalepus is one of those intermediate forms which connect 

 two tribes or circles ; allowing this, and that the Rutelidce also and Anoplognathidce are intimately 

 connected with the Dynastidce,^ we have another instance of unconnected ramifications, which lead 

 by different routes to different tribes. It may be here not out of place to observe, that in the true 

 Rutelidce, there is the vertical prosternum of the Dynastidce, and the horizontal projecting mesos- 

 ternum 2 of the Anoplognathidce, which last have no elevation of the prosternum. 



(179} 1. * Diplotaxis tristis. Sad Diplotaxis. 



D. f tristis J eastanea punctatissima ,- scutello lavi ; clytris puncto- scriatis : striis discoidalibus didijmis ; (arsis intermediis tibia 



longioribus ; antennis palpisque mfis. 

 Sad Diplotaxis, cbestnut, thickly punctured, scutellum without punctures ; elytra with punctures in rows, the discoidal 



rows paired ; intermediate tarsi longer than the tibia ; antennae and palpi rufous. 



PLATE V, FIG. 3. 



Length of the body 5 — 5J lines. 



Several specimens taken in Lat. 54°. Taken also in Novia Scotia by Capt. Hall. 



'• I call the canthus cleaving, when it appears to enter the eye. 

 s Hor.Entomolog. t. ii, /. 15, d. Mr. Mac Leay describes the mandibles as acute, but this appears a slip of the pen, 

 for they are obliquely truncated at the apex and concavo-concave, as Mr. Curtis has represented them. 



9 Introd. to Ent. iii, 368, B. " Hor. Ent. 67. 2 Introd. to Ent. iii, 378, C. 



