new Species of Hiateridte. 341 



attached to these structures. The mechanical action of the 

 etnarginate mesosternum is that a species, such as those 

 of Hololepta, Ilister, and Paro)naIus, can move the thorax 

 easily sideways, as the rounded-ofF base of the presternum 

 works freely to and fro in the mesosternal incision ; and 

 the mechanical utility of a projecting mesosternum with a 

 corresponding incision in the keel of the presternum, such as 

 that in Trypanceus and Pachycrcerus, is that by the close 

 fitting of the segments tiie one in the other the column of tiie 

 body is strengthened in forcing a way in a direct line through 

 any obstructed passage they may seek to enter. Trypanceus 

 especially finds obstacles in the holes of the Platypi and other 

 wood-boring species on which they feed. Marseul, in his 

 monograph, at first placed the " Trypaneens " after the 

 " Sapriniens," but in 1862 he installed them after the 

 ^^ Hololeptiens," leaving the genus Teretrius in the "Abreens " ; 

 but I think Teretrius and its allies caimot be separated from 

 the Trypancei. 



I have not overlooked the fact that the genus Hister, as 

 now constituted with its 365 species, has sometimes a truncate 

 mesosternum, sometimes a sinuous outline, and sometimes it 

 is markedly emarginate. Thomson founded the genus 

 AtJwlus, of which Ulster coi'vinus, Germ., is the type, but he 

 associated with it other very different species, such as 

 U. bimaculatus, L., and these, I think, cannot be set together. 

 Hister truticatisternus, Lew., from Central America, H. obtusi- 

 slernus^ Sch., from East Africa, and others from widely 

 distant places have truncate sterna, but are very dissimilar to 

 H. corvinus. In the genus Hister the mesosternum varies in 

 form ; in other genera, as in Omalodes, it is similar in all tlie 

 species. 



Ulster orientalis, Payk. (Men. p. 17, pi. xiii. fig. 7, 1811), 

 a common species in India and Ceylon, was omitted by an 

 oversight in my Catalogue. 



List of Species^ arranged generically. 



Hololepta obtusipes, Mars. Eblisia tenuipes, sp. n. 



Pygocoelis sp. Macrolister striatisternus, sp. n. 

 Teretriosonia sexuale, Schaeffer. Hister dauphini, sp. n. 



Plaesius hamatas, sp. n. Corvphseus violaceus, sp. n. 



asperimargo, sp. n. Notodoma satiirum, Leio. 



striatipectus, sp. n. Lissosteruus gracilipes, sp. a. 



Platysoma rimje, sp. n. Sapriuus sinaiticus, Crotch. 



Oylistosoma epilissum, sp. n. Abrseus fakir, sp. n. 



