2 CLAVICOEN1A. 



characters I have adopted, and beg here to express my obligation to their 

 work generally, but I cannot help thinking that their table of the 

 Clavicoru families (Introduction, p. xxxi) would tend far rather to 

 mystify than to instruct the ordinary student of Coleoptera, and yet it is 

 probably the best yet published ; in no group is a general acquaintance 

 with forms more needed, as there are a very large number of obscure and 

 closely allied genera contained in the various families ; every student, 

 therefore, is strongly recommended to make himself acquainted with as 

 many members of the group as possible superficially, before he begins to 

 study the complex as a whole. 



Hydrophilidae. This family is chiefly distinguished by the great 

 development of the maxillary palpi ; these in many instances are several 

 times longer than the antennae, which are inserted under the sides of the 

 front, and are composed of from six to nine joints and terminate in a 

 club, which is usually 3-jointed ; the abdomen is made up of five, rarely 

 seven, free segments ; the tarsi are all five-jointed, and the middle and 

 posterior tibiae are often ciliate and compressed for swimming ; the size 

 is very variable (from f mm. to 48mm.). 



Xieptinidae. Closely allied to the Silphidse, but differing in their 

 transverse mentum, long filiform antennae, small anterior coxae, very 

 short metasternum, and the fact that the sternal epipleurae of the elytra 

 are almost obsolete or very little pronounced ; eyes entirely wanting or 

 represented by translucent eye spots; size small. 



Silphidae. Mentum quadrate, antennae straight, inserted under the 

 margin of the front, 11-jointed, rarely 9- or 10-jointed, thickened 

 towards apex or more often furnished with a club ; eyes finely granu- 

 lated, sometimes absent ; thorax margined ; anterior coxae large, conical 

 and contiguous ; abdomen composed of five or six ventral segments ; 

 elytra often not covering the whole body ; legs sometimes stout, some- 

 times slender ; tibia3, as a rule, spinose externally ; tarsi usually, but not 

 always, 5-jointed; size very variable (|mm, to 30mm.). 



Scydmaenidae. Mentum transverse : antenna 11-jointed, inserted 

 upon the front, thickened or clavate ; maxillary palpi long with the last 

 joint very small ; anterior coxse subovate, contiguous ; thorax not or 

 scarcely transverse ; elytra covering the abdomen entirely or with the 

 pygidium rarely exposed (as in Euthia) ; abdomen with five or six free 

 ventral segments ; legs moderately long, tarsi 5-jointed with the claws 

 simple ; size very small. 



Clavig-eridae. Allied to the Pselaphidae, but distinguished by having 

 the joints of the antennae varying in number from two to six and the 

 palpi one-jointed and rudimentary ; the head is long and cylindrical, and 

 the basal segments of the abdomen are connate and deeply excavated ; 

 size very small. 



Pselaphidae. Mentum small, more or less quadrate ; antennae in- 



