362 [June, 



One specimen found at Eagle Harbor, Lake Superior. The description given 

 by me is imperfect, on account of the thin margins of the thorax having been 

 partly destroyed in the only specimen obtained : thus I have stated that the 

 thorax was sinuous on the sides, while in reality the outline of the disc only is 

 sinuous ; the lateral margins of the thorax being continuous and regular in their 

 outline. The discovery of the next specimen, which is precisely similar in 

 sculpture, though only half as large, has enabled me to correct this error. 



6. 0. fossatus, capite thoraceque viridi-seneis nitidis, hoc transversolateri- 

 bus rotundatis marginibus depressis diaphanis testaceis, disco convexo profunde 

 canaliculato, amice 6, postice 4-fossato, fossulis externis-in marginem impressis 

 (unde discus sicut in 0. nitido apparet), elytris testaceis convexis, punctis 

 inaioribus striatis, subtus seneo-niger, pedibus pallidis. Long. -045. 



One specimen found at the Colorado River, California. 



7. 0. Holmbergi, longiuscula capite thoraceque viridi-seneis, thorace sub- 

 transverso subcordato postice angustato, lateribus rotundatis postice subsinuatis, 

 transversim biimpresso, versus basin utrinque fovea magna parum profunda 

 obliqua notato, anticeque linea arcuata versus latera insculpto, elytris confertim 

 punctato-striatis. Long. -05. 



Maklin, (per Mannerh.) Bull. Mose. 1853. 



Peninsula of Kenai, Russian America; Baron Chaudoir. Nearly resembles in 

 form 0. interruptus Lee. but the thorax is less transverse, and more narrowed 

 posteriorly; the thorax is destitute of the dorsal lines seen in that species. The 

 medial channel is wanting in my specimen, but according to the description 

 given by Maklin, is sometimes visible, though faint. 



Hydrjena Kug. 



1. H. pensylvanica, atro-fu?ca, pal pis pedibus, tboracisque marginibus 

 testaceis, thorace subquadrato dense punctato ad latera impresso,ely tria subopaeis, 

 punctis confertis subquadratis seriatis. Long. -075. 



Kiesenwetter, Linn. Eutom. 4, 166. 



New York and Lake Superior ; sometimes quite abundant. As the only speci- 

 men examined by Mr. Kiesenwetter was found at New York ; the applicability 

 of the specific name is not obvious. The punctures of the elytra, although 

 described by him as round, appear to me quadrate, and the intervals are quite 

 distinctly elevated. 



2. H. punctata, longiuscula, supra piceo-tesfacea nitida, capite tboracis- 

 que disco infuscatis, hoc subquadrato minus subtiliter sat dense punctato, ad 

 latera longitudinaliter impresso, elytris punctis rotundatis sat dense seriatim 

 positis, palpis pedibusque testaceis. Long. -95. 



Pennsylvania, Rev. D. Ziegler. This species i3 larger and narrower than the 

 next, which at first sight it resembles : the thorax is more coarsely punctured, 

 and the sides are distinctly impressed for the whole length. 



3. H. marginicollis, nitida, capite thoraceque nigris hoc antice posti- 

 ceque testaceo, subtilius minus crebre punctato, subquadrato, lateribus antice 

 late foveatis ; elytris piceo-testaceis punctis rotundatis sat dense seriatis, palpis 

 pedibusque testaceis. Long. -05. 



Kiesenwetter, Linn. Ent. 4, 177. 



New Orleans, Dr. Schaum and Mr. Wapler. One sex is a little broader than 

 the other, but in neither is the thorax one half wider than long as described by 

 Kiesenwetter : the large broad fovea at the side of the thorax before the middle 

 is not mentioned by him, although he states that the longitudinal lateral impres- 

 sions are almost wanting. Notwithstanding these discrepancies, I must regard 

 my specimens as authentic, one of them having been received by me from Dr, 

 Schaum as a type. 



