94 NORTH AMERICAN 



Tarsus iiuth a single claw ; front of head not produced: antennae straight. 



First ventral segment much elongated ; prosternnm neither foveate nor cari- 



nate ; last joint of antennae abruptly very robust Trimium. 



First three segments of the abdomen sub-equal ; prosternum bifoveate ; last 

 three joints of the antennae more or less gradually increasing in width. 

 Eyes present. 



Prosternum not carinate Euplectus. 



Prosternum and mesosternum having a distinct medial loii^'itiiiliiial 

 carina ; tenth joint of antenna unusually long and conspiiuous. 



Thesium. 

 Prosternum carinate ; mesosternum not carinate. 



Eyes well developed and large in both sexes ; antennae very slender, 

 club very slender and elongate ; pronotum having two lateral 

 canaliculations, but neither a transverse basal groove nor lateral 



loveae ; prosternum very short Faliscus. 



Eyes small and very coarsely granulated in the male, rudimentary in 

 the female ; pronotum wi)h lateial foveae and transverse basal 

 groove, without lateral canaliculations ; club of antennae rnlmst ; 



prosternum very long Nicotheus. 



Eyes wanting ; prosternum liaving a distinct medial carina. ..Eutyphlus. 



I liave, much to my regret, been unable to obtain Dr. LeConte's 

 types of Trimium, and since Eutyphlus contains but a single well- 

 known species, it is proposed at the present time to treat of the four 

 remaining genera alone. Reitter, in his recent tabular statement of 

 the Pselaphidae, distinguishes bis genus Scotoplectus, into which he 

 absorbs Eutyphlus Lee, by the abnormal shortness of the elytra ; as 

 in Eutyphlus the elytra are normally much longer than the prothorax, 

 I cannot witiiout further evidence make the change of name. 



EUPI.ECTUS Leach. 

 The species of this genus are more numerous and individually much 

 more abundant than tliose of the others ; tliey are vei-y readily divided 

 into two groups, depending upon the canaliculation or not of the pro- 

 notal disk. As a coincidence, and probably of no generic import, it 

 is to be remarked tiuit the species witliout tlie pronotal canaliculation 

 liavf the entire lower surface of the liead covered densely with long 

 erect sensitive setae, wliile, with but one or two exceptions, these 

 setae are entirely wanting in those with canaliculated pronotum. It 

 is inferred tliat the setae are sensitive, since tlie tip of each is swollen 

 into a bulbous knob, but why some of them should be provided with 

 this additional sensory apparatus, while others, apparently similar in 

 all other respects, should be entirely deprived of it, is one of the 

 mysteries of nature which must probably forever remain unsolved. 



