226 [January, 



Descriptions of Tivoity new .species of Cohoptera itihahiting the Uuiled States. 



By John L. Le Conte, M. D. 



The following; are a few remarkable species of families which are so small as 

 not to be of sufficient importance for a special essay, or else they belong to 

 groups which, having already furnished material for synopses or monographs, 

 are not sufficiently increased to need revision. Some new genera are proposed, 

 the affinities of which, so far as made out, will be detailed below ; the names of 

 the families to which the new genera belong are appended to each. Species in- 

 dicated from the Mexican Boundary, were collected by Mr. J. H. Clark, under 

 Col. J. D. Graham, and were kindly communicated to me by my friend Dr. S. F. 

 Baird. 



Amsomera Brulle. (Dytiscidre.) 



Palpi cylindrici, labiales articulo penultimo lon^iore; prosternum non com- 

 presso carinatum, postice productum ; tarsi anteriores filiformes articulo ultimo 

 elongato, postici parce ciliati, articulis Imo 5toque elongatis, unguiculis binis 

 aqualibus mobilibus. 



Having several specimens of a species of this interesting genus from New 

 Mexico, I am able to complete the description of Brulle and Aube, which Avere 

 taken from a specimen deprived of its posterior feet. These organs are slender; 

 the tibice are slightly ciliated internally with long hairs, and armrd at the tip 

 with two slender, subequal spurs ; the posterior tarsi are not longer than the 

 tibiae, slightly compressed and sparsely ciliated ; the first joint is as long as the 

 second and third ; the 2d, od and 4th are nearly equal ; the 5th is a little shorter 

 than the 3d and 4th, not narrowed towards the extremity ; the claws are equal 

 and moveable In the male, the first three joints of the anterior and middle 

 tarsi are sl'ghtly dilated, and furnished beneath with feathery papillae, very 

 much as in Platynus. The posterior tibiae of the female are scarcely ciliate. 



This genus appears quite as closely allied to Agabus and Copelatus as they 

 are to each oth^r. The form of the thorax would indicate, however, that it 

 must be rec^-ived as a distinct genus, but the characters, on close examination, 

 appear to be of little value ; the bfst differences are found in the elongation of 

 the last joint of the anterior and middle tarsi, the smaller size of the spurs of 

 the posterior tibiae, and the more regular form of the posterior tarsi, which are 

 not attenuated at the apex. The middle lobe of the mentum in the species here 

 described is broad, short, and very obsoletely sinuated, while the mentum of 

 Anisomera is described as having the middle lobe slightly prominent in the 

 middle; this character must be re-examined with other specimens, as, if it be 

 correctly described, the present species cannot be associated with the type of 

 the genus; the prosternum is less compressed than in Copelatus. Agabus is 

 described as having the prosternum strongly compressed and carinate ; this 

 structure is found in A. t a n i a t u s Anhc, and many others, but is hardly to be 

 observed in A. s t r i at u s yl/^/;f. I would also observe that Agabus a n- 

 g u st u s Lee. (Agassiz. Lake Sup., 213) by having the thorax much rounded 

 before, and nearly parallel behind the middle, shows a tendency towards the 

 peculiar form seen in Anisomera. 



A. cordata, supra aeneo-picca, elongato-ovalis, depressa, subtilissime re- 

 ticulata, thorace brevi, postice angustato, et lateribus sinuato, elytris thorace 

 vix latioribus, postice non dilatatis ; subtus nigra, ore antennis pedibusque ru- 

 bro-piceis. Long -45. 



Santa Fe, New Mexico. Mr. Fcndler. Varies, with black feet ; the sides of the 

 thorax are strongly rounded in front, and subsinuate behind ; the base is as 

 wide as the ap^x, the anterior dilatation being produced by the curvature of the 

 sides ; the anterior angles are acute, the posteridr angles rectangular. The 

 elytra are very little wider than the widest part of the thorax, regularly elongate, 

 eiiqitical, with the usual series of punctures becoming irregular towards the tip. 



