12 BYKSOPID^. [LeConte. 



Meso- and metasternura very short, side pieces of the latter not separate. 



Elytra connate, covering the pygidium. 



Abdomen with the first and second ventral segments very large, connate, 

 the suture effaced at the middle ; third and fourth short, fifth as long as third 

 and fourth united ; sutures straight, very deeply impressed ; intercoxal 

 process broad. Anal segment of (^ small, rounded at tip. 



Anterior coxae small, contiguous, rounded somewhat prominent ; middle 

 coxa? separated, small, rftunded ; hind coxae small, oval, widely separated, 

 distant from the side of the elytra. 



Legs slender ; tibiae sinuate on inner side, truncate at tip, and armed 

 on the inner side with two small terminal anchylosed spurs. Tarsi 4- 

 jointed, narrow, joints cylindrical, setose or spinose beneath. Third joint 

 not at all dilated or bilobed in Thecestenms. Claws slender, simple, sepa- 

 rate. 



This family contains but a small number of genera, all confined to the 

 Eastern continent, except Thecesternus which is restricted to the interior 

 parts of the United States, extending into Texas and eastward to Illinois. 

 It forms a tribe distinguished from other Bja-sopidae by the peculiar con- 

 formation of the prosternum, which forms a triangular plate in front of the 

 coxae. 



THECESTERNUS Say. 



I have described (Proc. Acad. Nat. Sc, 1856, 18) what I at that time 

 believed to be six species of this genus, in addition to the one described by 

 Say. Subsequent investigation with niore abundant material has raised 

 some doubt in my mind as to the validity of the specific differences which 

 I then observed. 



It is quite evident that there are several species, but it is found quite im- 

 possible to define them. There are all gradations from specimens ( T. Jiume- 

 ralix) in which the humeral processes are fully one-third as long as the 

 prothorax, to others (T. morhillosus) in Avhich the elytra are truncate at 

 base, and the humeral angles only slightly prolonged. 



It may be regarded therefore as a genus in which the originally distinct 

 species are becoming effaced by mixture. 



The specimens which I collected in Kansas were found under dried 

 buffalo-dung. I have since received several individuals from Illinois, 

 Texas, and Missouri ; upon one of the latter is this note, made by Mr. C. 

 V. Itiley : "Cutting off blossoms of grapevines in May ; also beaten from 

 Carya." 



■ Well preserved and'Clean specimens are mottled with a pale ochreous crust 

 composed of closely adhering minute scales. The bibliography is as follows : 



1. T. humeralis Say, Cure. 8 ; ed. Lee. 1 207; Lacord., Gen. Col. pi. 67, 

 f, 3; Bracliycents liumer. Say, J. Ac. Nat. Sc. Phil, v, 254; ed. Lee. ii. 

 316 ; Lithodus humer. Germ., Sch. Cure, ii, 420 ; Lee. Pr. Ac. Nat. Sc. 

 1856, 18. Varieties? Lithodus rectun, affinU, rudis, erosus Lee. ibid, 18; 

 longior morbillosus Lee. ibid., 19. 



