164 H. C. FALL. 



individual variation in the number of joints has been observed in 

 these species. 



Our species of Oligomerus seem as a rule to be rather rare, and 

 few collections contain all told more than half a dozen specimens. 

 In the LeConte collection there are 5 serieans, 2 obtusus, 1 alter 

 nans and 1 brevipilis: in the Horn collection 2 serieans, 1 obtusus 

 and 2 alternans. Mr. Blanchard writes me that he has 2 serieans 

 and 4 alternans, all taken about thirty years ago. The Hubbard 

 and Schwarz collection contains all the species, but in the material 

 sent me there are only twelve examples, a number, however, greater 

 than any other collection offers. The material before me numbers 

 between sixty and seventy specimens, in which six species seem to 

 be clearly indicated. Of these, serieans and tenellus are evidently 

 aberrant. The species may be distinguished as follows : 



Front coxae distinctly separated, intercoxal process wider, not laminate poste- 

 riorly. 



Antennae 9-jointed, disk of prothorax distinctly gibbous, pubescence entirely 

 reclinate 1. tenellus. 



Antennae 10-jointed, disk of prothorax scarcely gibbous, pubescence of bead 



and thorax erect 2. serieans. 



Front coxae contiguous or virtually so, intercoxal process laminiform posteriorly, 

 disk of prothorax more or less distinctly gibbous. 



Auteunae 10-jointed, pubescence short, sparse and perfectly recumbent; elytral 

 striae finely punctate; intermediate joints of antennae distinctly longer 

 than wide, ninth joint a little longer than the three preceding in the 

 female 3. calilbrnicus. 



Antennae 10- or 11-jointed ; pubesceuce entirely recumbent without trace of 

 erect hairs; elytral striae more coarsely punctate; intermediate joints 

 of antennae very sbort and transverse, the ninth joint equal to the five 

 preceding in the female 4. obtusus. 



Antennae 9-jointed. 



Eecumbent pubescence of upper surface with intermixed short erect hairs. 



5. brevipilis. 

 Surface without evident erect hairs; alternate elytral interspaces more ele- 

 vated in typical examples, but frequently scarcely at all so. 



6. alternans. 



1. O. tenellus n. sp. — Very elongate, moderately depressed, red-brown, 

 pubescence very short, reclinate. Antennae 9-jointed, joints 2 and 3 subequal, 

 narrower than the first and nearly two-thirds as long; 4-6 subequal, a little 

 shorter, and more slender than 3, all distinctly longer than wide ; 7 and 8 simi- 

 lar, each very slender and nearly as long as the five preceding, 9 longer, fili- 

 form. Front slightly less than twice as wide as the vertical diameter of the 

 eye. Prothorax similar in form and sculpture to obtusus, the disk distinctly gib- 

 bous. Elytra four times as long as the prothorax, fully two and one-fourth times 

 as long as wide; very feebly striate punctate. Prosternum before the coxae but 



