NATURAL SCIENCES OP PHILADELPHIA, 351 



Legs rufous or testaceous, body black : 



Thorax finely sparsely punctured 24. pedal is. 



Thorax coarsely sparsely punctured 25. texanus. 



Black, elytra and legs rufous 26. r u fipe n n i s. 



b. Sides of thorax distinctly serrate: 



Entirely black, elytra densely punctured 27. serrulatus. 



Black, elytra and legs rufous 28. serricoll is. 



- Group I. Byturosomus Motscb. 



But one species of this group is known to_ me. It is of oblong oval form, 

 rather more robust than the other species ; the prothorax is twice as wide as 

 the head, and in the male is wider than the elytra ; it is wider than long, 

 broadly rounded on the sides, and obliquely subsinuate each side at the base; 

 the angles are all rounded. The pubescence of the thorax is less dense than 

 that oi' the elytra ; a few longer suberect hairs are intermixed with the pros- 

 trate ones. The front tibiae are longer than usual, slender and slightly 

 curved in the male, and the row of small spines on the outer side is very 

 distinct. The appendages of the claws are broad, and connate with the claw ; 

 the outer one is free for a very short distance. 



1. P. fuscus. Dasytes fuscus Lee. Pr. Ac. N. Sc, vi., 169. Byturosomus 

 griseus Motscb. Bull. Mosc. 1859, ii., 395. B. rufipes Motscb. ibid. 



Vallecitas, San Diego County, California ; May. The differences between 

 the sexes are. so great that unless found together they might be readily con- 

 sidered distinct species ; in the male the thorax is wider than the elytra, and 

 much less densely pubescent ; the elytra are gradually narrowed from the 

 base; the abdomen is composed of six ventral segments, and the front tibiae 

 are elongated, and curved inwards : in the female the body is not attenuated 

 behind, the thorax is as wide as the elytra, gradually narrowed in front, aud 

 densely pubescent ; the abdomen has but five ventral segments, and the ante- 

 rior tibite are not curved. In both sexes the fourth joint of the antenna' is 

 narrower than the fifth, though somewhat triangular. 



Col. Motschulsky has by some accident interchanged the names of D. 

 fuscus and D. griseus Lee. Of the latter I had but a single specimen, 

 and was therefore unable to furnish him with a type; D. fuss us, on the 

 contrary, was collected by me in large numbers, and has been freely distri- 

 buted. 



Group II. Trichochrous Motsch. 



In this group the body is elongate, or elongate oval, the thorax not more 

 than one-hnlf wider than the head ; the pubescence is prostrate without any 

 intermixed hairs, though in some species (antennatus, brevicornis, 

 &c.) clothed with long and coarse pubescence, the hairs lie less closely on the 

 surface than in the others. The characters given in the synoptic table will 

 enable the species to be recognized without difficulty. 



2. P. ater. Pristoscelis atrus Bland. Proc. Ent. Soc. Phila., iii., 253. 

 Abundant near San Francisco. This species ditfers from P. 1 a t i c o 1 1 i s 



by the larger size, by the thorax being more distinctly transverse, with the 

 sides less rounded, and the posterior angles more distinct, although obtuse; 

 the sides of the thorax, as in the next two, are fringed. 



3. P. oregonensis, elongatus, piceo-seneus, dense cinereo-pubescens, 

 thorace longitudine sesqui latiore, lateribus fimbriatis late rotundatis, apice 

 late emarginata, basi late rotundata, angulis anticis subacutis, posticis obtu- 

 sis baud rotundatis, disco subtiliter sat dense punctato ; elytris modice con- 

 vexis, confertim subtiliter punctatis ; subtus nigricans, antennis palpisque 

 nigris, tibiis tarsisque picescentibus. Long. 3-5 4 mm. 



Oregon, and at Fort Crook, California, Dr. G. H. Horn. This species is 



1866.] 



