290 GEO. H. HORN, M. D. 



Group XVIII, maculicoUis. 



In this group are placed three species of small size and of a fticies 

 quite different from all the preceding species, and presenting charac- 

 ters of almost generic value. The spurs of the hind tibiae are free 

 in both sexes ; antennse 9-jointed ; claws with a small l)asal tooth. 

 Last ventral segment small ; anterior tibiae bidentate, the upper tooth 

 being entirely wanting ; the anterior border of the thorax distinctly 

 thickened. 



The importance of most of these charactei's has already been al- 

 luded to by Dr. LeConte, but the bidentate front tibite seem to have 

 escaped observation. He has, however, directed attention especially 

 to the thickening of the front margin of the thorax and the slight 

 pointing thereby in the direction of Listrochelus. In one of the 

 species {maculicoUis) there is on the occiput a similar transverse ridge, 

 which prevents the head from being too far retracted, and to which 

 I have directed attention as a characteristic of the vast majority of 

 the species of that genus. 



In the group as at present constituted the clypeus is entire, feebly 

 truncate in nitidula, and the hind angles of the thorax are well de- 

 fined in but one species. It is worthy of note that one species has 

 the clyj)eus slightly coarctate at base as in criiiifa and tristis. 



The three species may be separated in the following manner : 



Thorax with a large, indistinctly limited piceous space. 



Hind angles of tliorax rec^taugular ; head with punctures not close, front flat; 



margin of body not ciliate ; legs testaceous, not ciliate 79. tiisa. 



Hind angles of thorax very obtuse; head roughly cribrate, front convex ; mar- 

 gin of body fimbriate with moderately long hair; femora yellow, tibite 



and tarsi piceous, legs ciliate 80. Ilistciilicolli^. 



Thorax entirely pale yellowish testaceous. 



Hind angles of thorax broadly rounded ; head with very coarse punctures in 

 two groups ; margin of body with short cilise ; legs testaceous, not ciliate. 



81. nitidula. 



These species are all from the southwestern limit of our fauna, the 



first from Texas, the others from Peninsula of California. 



79. Ij. tiisa u. sp. — Moderately elongate, subdepressed, slightly broader be- 

 hind, beneath pale yellowish testaceous, thorax with large anterior piceous spot, 

 elytra testaceous, but darker than the under side, surface moderately shining. 

 Head piceous, shining. Clypeus concave, entire, the margin broadly reflexed, 

 ])unctuation coarse and close, front flat, similarly punctured. Thorax narrower 

 in front, apical border distinctly thickened, sides strongly arcuate in front, nearly 

 parallel posteriorly, margin entire, cilire distant and short, hind angles distinct; 

 disc with coarse punctures, less deeply impressed toward the sides, very regu- 

 larly, but not closely placed. Elytral punctures coarser, closer and deeper than 



