2 HETEROMERA. 
and California) constitute this genus; two of these species occur also within our 
boundary. og : 
They are found beneath stones in arid districts. 
A closely allied genus (Stidia, Horn) is also found in California. 
1. Triorophus levis. 
Triorophus levis, Lec. Ann. Lyc. New York, v. p. 141'; Horn, Revis. Ten. N. A. p. 259(1870)*; 
Lac. Genera, t. 48. f. 4. 
Triorophus rugiceps, Lec. loc. cit. p. 142°. 
Hab. North America 123%, Tejon in California to the western base of the Rocky 
Mountains in Arizona.—MeExico, Northern Sonora (Morrison). 
2. Triorophus nodiceps. 
Triorophus nodiceps, Lec. Proc. Acad. Phil. vi. p. 447*; Horn, Rev. Ten. N. A. p. 259 (1870) ’; 
Thoms. Arcana, i. t. 13. f. 7. 
Hab. Norra America 12, Texas.—Mexico, Monclova in Coahuila (Dr. Palmer). 
Two examples from Monclova agree fairly well with the description of 7. nodiceps, 
except that they have the anterior angles of the thorax a little more acute and 
swollen. 
TRIENTOMA. 
Trientoma, Solier, Ann. Soc. Ent. Fr. iv. p. 256, t. 5. f. 7-10 (1835) ; Lac. Gen. Col. v. p. 35 (1859). 
Two species of this genus are recorded from Cuba and St. Domingo; others from the 
West Indies, undescribed as yet, exist in collections, and we now have to add two from 
Mexico. 
Allied genera (Triphalus and Trimytis) occur in North America. 
1. Trientoma mexicana. 
Ovate, smooth, dull black, opaque. Head almost impunctate, coarsely wrinkled on each side; prothorax 
strongly transverse, widest just before the base, slightly rounded at tho sides, narrowed in front, smooth ; 
elytra with nine rows of very indistinct almost obsolete rounded punctures, the punctures a little more 
distinct towards the sides, obsolete behind and towards the suture. 
Length 6-7 millim. 
Hab. Mexico (coll. F. Bates). 
Two examples. Extremely close to T. sal/@i from St. Domingo, and only differing 
therefrom by being a little more opaque, the sides of the thorax straighter, and the 
antenne not quite so stout. 
2. Trientoma rugifrons. (Tab. I. fig. 1.) 
Black, shining. Head strongly trilobed in front (the middle lobe of the epistoma long and the lateral lobes 
swollen and prominent), coarsely and closely punctured, and strongly wrinkled longitudinally on each 
