NATURAL SCIENCES OF PHILADELPHIA. 393 



Specimens of this species from Montana have been subsequently described 

 by Mr. Bland, under the name C. brunnipes (Proc. Ent. Soc. Phil. iii. 67). 



It occurs at Pembina, and various other places in Hudson Bay Territory, 

 and also in Montana and the interior of Oregon and Washington Territory. 



ANAMESUS Lee. (n. g. Elateridre). 



A. convexicollis, 9 alatus, piceus, pubescens, capite confertim punc- 

 tato, fronte vage triangulariter iiupressa, oculis parvis lateralibus ; thorace 

 latitudine baud longiore, lateribus subparallelis, antice subrotundatis, angulis 

 posticis paulo divergentibus, acutis carinatis, disco convexo, subtilius punc- 

 tate ; elytris abdomine duplo brevioribus apice singulatim rotundatis, striis 

 baud punctatis, interstitiis punctulatis ; antennis subserratis, capite sesqui 

 longioribus, articulo 2ndo sequente paulo breviore. Long. 21-5 mm. 



One specimen from Nevada in Mr. Ulke's collection. The abdomen has 

 seven ventral segments, the five seen ordinarily in Elateridse being increased 

 by the first, (usually concealed behind the coxae, ) becoming visible, and by the 

 addition of an apical segment as in the 9 f Euthysanius (Proc. Acad. Nat. 

 Sc. Phil. 1859, 74). In the latter, however, the number of visible segments 

 is eight. 



The wings are well developed, and folded under the elytra, which are only 

 one-half the length of the abdomen. 



Corresponding with the female above described is a male in Mr. Ulke's col- 

 lection, from Fort Tejon, California. The sculpture is the same; the eyes are 

 large and prominent ; the antenna? are longer than the head and thorax, 

 strongly serrate, with the external angle of the joints 2 10 acute ; the third 

 joint is similar to the fourth, though smaller. The elytra are as long as the 

 abdomen, somewhat dehiscent behind, and acute at tip, paler in color than the 

 head and thorax. The abdomen has six visible ventral segments, the last be- 

 ing provided with lateral pieces, as in the males of the allied genera. Length 

 13-5 mill. 



I regard this as the male of the Nevada species, and, as indicating a new 

 genus, differing from Aplastus by the (usual) 5th ventral segment being 

 truncate at tip in both sexes, fully exposing the sixth segment; the fifth seg- 

 ment in Aplastus is rounded at tip, and the sixth retracted. 



The two specimens of Aplastus optatus in my collection differ greatly in the 

 form of the antennae ; the one from Mr. A. Murray has the joints 4 10 more 

 strongly triangular, and more produced at the outer angle, than the specimen 

 found at Bodega (Cal.) by Mr. George Davidson. I was therefore induced to 

 regard the latter as a female, a view that is confirmed by the different struc- 

 ture of the last ventral segment in the two individuals ; the lateral valves, 

 quite conspicuous in the male, are absent in the supposed female. 



The tribe Plastocerini thus exhibits in Western America a very beautiful 

 series of gradations from Aplastus, in whi h the sexual differences are slight, 

 through Ananiesus, where the elytra are shortened, and the ventral segments 

 increased in number, to Euthysanius, in which the ventral segments are still 

 farther increased, the abdomen excessively elongated, the elytra very short, 

 and the wings wanting. The female of Plastocerus is not yet discovered. A 

 correspondence with this regular degradation is seen in the form of antennae, 

 serrate in Aplastus, and Anamesus ; not greatly unequal in the sexes of the 

 former, much shorter in the female of the latter ; pectinate, with long 

 branches in males of Plastocerus and Euthysanius, 11-jointed in the former, 

 12-joiuted in the latter. 



PLASTOCERUS Lee. 



P. frater, piceo-castaneus, elytris dilutioribus, helvo-pubescens, capite 

 thoraceque pilis longioribus vestitis, illo scabro, hoc latitudine paulo breviore, 

 lateribus antice valJe rotundatis, angulis posticis divergentibus, carinatis, 



1866.] 



