BYRRHID^E 57 



Tribe BOTHRIOPHORINI. 



The different facies due to the very minute size of the body, 

 together with the radically different structure of the antennae and 

 method of protecting them in repose, would seem to suggest a 

 distinct tribe for species of the Bothriophorus type, though in most 

 of their structural characters they are distinctly foretokened in 

 Limnichus, the more general features of the head, under surface, 

 legs, crural cavities and vestiture being almost identical; this 

 however means subfamily relationship rather than tribal. There 

 are two genera as follows: 



Antennse with a gradually enlarged and rather compact, 3-jointed club, 

 preceded by but one small joint. [Type B. atomiis Muls.]. Palae- 

 arctic *Bothriophorus 



Antennae with a 2-jointed club, preceded by three equal small joints, the 

 last joint notably large, shining, oval and bristling with long sparse 

 hairs, which are nearly wanting basally; first joint rather shorter 

 than the second and somewhat concave on its upper surface to 

 receive the rather prominently rounded sides of the front just behind 

 the epistoma and over the point of antennal insertion. [Type P. 

 minutus Lee.]. Nearctic (Sonoran) Physemus 



The joints in the basal and distally tapering part of the antennae, 

 in both these genera, are very closely united and separated by close 

 transverse lines of contact; they are n-jointed in both. A diagram 

 of the antenna of Physemus minutus (Ditaphnis scymnoides Csy.) 

 may be found in the Bulletin of the California Academy, II, 1886, 

 plate VII, fig. 18. Bothriophorus Muls., is exclusively European; 

 its type, atomus Muls., resembles Physemus minutus very closely to 



external view. 



Physemus Lee. 



Ditaphrus Csy. 



The generic characters of Physemus reproduce those of Limnichus, 

 with the exception noted above. The head is very similar in being 

 convex at the sides before the eyes, with a short transverse epistoma, 

 separated from the front by a deep suture and with a deep impression 

 on the sloping sides of the front behind the antennae, the eyes being 

 subvertical and unusually coarsely faceted. As leading toward 

 Physemus and Bothriophorus, it may be noted that the antennae 

 in Limnichus and Limnichoderus are partially sheltered in depres- 

 sions, feebly defined at the base of the head itself but not involving 

 the pronotum. The antennae however are short, very stout basally 



