566 Mr. T. Vernon Wollaston on the 



(or, more strictly, perhaps, to the same cluster of types), 

 peculiar, apparently, to the islands of the Malay archi- 

 pelago ; and yet I scarcely think that they could be 

 regarded as representing even distinct sections of a single 

 group. At any rate, if I were to treat them now as such, 

 I feel that the time would assuredly arrive when (as 

 I have lately done with the forms which cluster around 

 Mesites) they would be separated; and hence I have 

 thought it desirable to forestall that event by detaching 

 them at once. 



With this preliminary remark, I may state that Homalo- 

 trogus differs from Glceotrogus in its type being a little 

 more evidently (though at the same time very lightly) 

 sculptured, and not so highly polished ; in its head being 

 much narrower, more convex, and oval (instead of flattened 

 and subquadrate) ; in its eyes being consequently less 

 widely separated ; in its rostrum being much longer and 

 more convex, and (instead of nearly parallel) with the hinder 

 half comparatively slender and contracted, and with there- 

 fore the anterior one suddenly dilated (much as in Cos- 

 sonus) ; in its prothorax (which is exceedingly even) being, 

 if anything, squarer still, though more evidently constricted 

 at its extreme apex ; in the last three segments of its 

 abdomen being margined behind with a row of large 

 punctures; in its antennae (which are inserted conspi- 

 cuously before, instead of behind, the middle of its much 

 longer rostrum) having their scape straighter and less 

 outwardly curved, and only obsoletely truncate towards the 

 inner apex (and therefore with but a very slight tendency 

 for the anguliform projection which is so marked a feature 

 in Gloeotrogus), and having their second funiculus-joint 

 appreciably less shortened ; and in its legs being longer, 

 with the femora (at any rate the posterior four) somewhat 

 less clavate, and with the tibise less abbreviated. Judging 

 from the labels which are appended to them, the types 

 now before me (which are from the collection of Mr. 

 Pascoe) were taken by Mr. Wallace in the islands of 

 Coram and Batchian, of the Malay archipelago. 



82. ISOTROGUS (nov. gen.). This genus makes a nearer 

 approach to the normal Cossonus pattern than either of 

 the preceding two ; yet it certainly is not identical with 

 that group, its extremely flattened body and unimpressed 

 prothorax, and the peculiar construction of its scape 

 (which is biflexuose, and shows a more distinct tendency 



