1G6 GEO. H. HORN, M. D. 



me, resembles it even in specific characters. The connate ventral seg- 

 ments, however, forbid its entrance into the group, unless that charac- 

 ter should have escaped notice in tlie genus above named. The anten- 

 nae are ten-jointed in the present genus and but nine-jointed in Chnan- 

 nantliHs, though this would hardly warrant generic separation without 

 the presence of other characters. I place the genus provisionally 

 among the Oncerini of Leconte, although equally out of place by the 

 presence of the anterior tibial spine. As in Oncerus and Lasiopiis the 

 abdomen is rather small and the segments connate. The position of 

 the Oncerini among the Laparostict Jlelolonthidae, seems somewhat 

 objectionable, as the spiracles in Oncerus are placed ''on the dorsal in- 

 flexed portion of the ventral segments," (Lee. S//nopsis Mdolonthuhr, 

 Jour. Acad., 1856,) as in the genuine Melolonthidae, while the connate 

 abdominal segments of Oncerus^ Lasiopus and Acrafus is a character 

 at variance with the Glaphyrini, to which the division of Laparostict 

 Melolonthidne of Leconte, for the most corresponds. These genera may 

 form a sub-tribe of Melolonthidae near the Sericoidini, in the position 

 originally assigned them in the monograph above cited, or Acrafus may 

 be placed among the Chasmatopterides after Chnatinantlius. 



A. flavipennis, black, slightly glossy; head black, rather coarselj' and dense- 

 ly punctured, narrowed in front. Thorax black, broader than long, base and 

 sides rounded, anteriorly emarginate, less densely punctured than the head; 

 posterior and lateral margins ciliate with whitish hairs. Head and thorax 

 with short suberect hair. Elytra yellow-testaceous, oval, sparsely punctured, 

 and with a short yellow hair arising from each puncture. Mentum with a brush 

 of yellow erect hair beneath. Feet yellowish. Length .15 — .18 inch. 



The under surface of the insect varies in color in different individu- 

 als, in some being entirely black, in others with the abdomen yellow- 

 ish. 



This insect is found in tolerable abundance in April, on the flowers 

 of Larrea mexicanaj on the sandy desert east of Antelope peak, and on 

 the banks of the Gila River, Arizona. 



PLECTRODES, nov. gen. 

 Head quadrate. Epistome broad, thickened in front, concave above, 

 separated from the front by a slightly raised line. Labrum distinct, 

 emarginate. Mandibles thick, obtuse, not prominent. Maxillto short, 

 with two or three obtuse teeth at apex. l*alpi moderate, first joint 

 small, last joint longer than second and third together, deeply channel- 

 ed on its outer face. Mentum quadrate, concave, sides rounded. Li- 

 gula short, transverse, connate with the mentum, corneous. Palpi 

 short, last joint rather larger. Antennae ten-jointed, first joint equal 



