AMERICAN COLEOPTERA. 249 



HYDROPHILID.E.* 



Helophorus. — The species of this genus may be grouped as fol- 

 lows : 



A. Second joint of hind tarsi obviously longer than the 3rd; elytra without 

 scutellar stria. — (e. g. lineatus and all other N. American species except scaber.) 



B. Second joint of hind tarsi obviously longer than the 3rd; elytra with dis- 

 tinct scutellar stria near the suture. — (e. g. grandis of Europe.) 



C. Second joint of hind tarsi not longer than the 3rd; elytra with distinct 

 scutellar stria near the suture. — -(e. g. scaber.) 



Hydrochus impressu3 Zimm. — Long. H — Is lines. Above coppery green or 

 blackish, beneath brown ; prothorax broader than long, shallowly foveate, deep- 

 ly but not confluently punctured; intervals of the elytra slightly convex, al- 

 most as wide as the strise,5th depressed at the middle, but both in front of, and 

 behind the impression elevated, as is also the 4th opposite to the impression. 

 Carolina. [A distinct species near variolatus Lee. but among other differences 

 with wider and less deeply impressed prothorax.] 



Hydroohus vagus Lee— Specimens of this species undistinguisliable from 

 those collected in California have occured in South Carolina. 



Berosus immaculatus Zimm. — Long. U — H lines. Above grayish-yellow: 

 beneath and legs ferruginous-yellow; head and two spots on the front margin 

 of the prothorax metallic-green; mouth and clypeus yellowish. Smaller and 

 narrower than [aculeatus Lee], with the head and prothorax more equably 

 punctured; front with a shallow fovea, and no posterior elevated longitudinal 

 line; elytra immaculate, pointed behind, with the strise and intervals distinctly 

 punctured. — Carolina. [Also found in Illinois.] 



Hydrophilus nimbatus Say. — Differs from the South American lateralis Fabr.: 

 the yellow side margin is narrower and does not extend upon the front mar- 

 gin of the prothorax; the hind tibije are often almost entirely testaceous, the 

 elytra very finely, but visibly striate, and the anal tooth long and sharp, (in 

 lateralis scarcely visible). 



[If this determination be correct, as I have no reason to doubt, with 

 the specimens before me, then the Californian H. limhalis approaches 

 more nearly to the Brazilian lateralis in the yellow margin being wider 



22. Feronia carhonaria Dej.^muta Say. 



23. Myas cyanescens Dej.^=/ovea<w.s Lee. and not coracinus Say. 



24. Cratocara Lec.^Polpochile t-olier.^l/e/aKO^M.s |j Dej. The name given by 

 Solier should be adopted, in preference to the two others. 



Upon these synonyms, which constitute a most important addition to our 

 bibliography, since they dispose of many doubtful or unknown species men- 

 tioned in my List, I have merely to observe that they differ in three instances 

 (Nos. 19, 20 and 22) from the determinations of Dr. Zimmermann as contained 

 in the MSS. above printed, but must be regarded as entirely final and conclu- 

 sive, having been founded upon actual comparison of typical specimens, while 

 the results both of Dr. Zimmermann and myself were obtained from the study 

 of descriptions, often perhaps too imperfect or ill-defined to be of much value. 



* No reference is here made to the MSS. relating to Dytiscidse and Gyrinidse, 

 as I am now occupied in preparing special memoirs upon those families. — Lkc. 



