THE LONG-TOED WATER BEETLES. 681 



I). Form subdepressed ; thorax with sides strongly rounded, its disk 

 with three oblique tubercles each side of the median channel. 



CBENATUS. 



lih. Form elongate, convex ; sides of thorax less rounded, more or less 



sinuate at middle. 



c. Thorax scarcely broader at base than apex; pale stripe of elytra 



always entire. 1300. bioabinatus. 



cc. Thorax distinctly wider at base than apex ; pale stripe of elytra 



broadly interrupted at middle. 1301. sunxiATUS. 



S. linearis Zimm. and S. crenatus Say have both been recorded 

 from Cincinnati by Dury. 



1300 (3949). Stbnelmis bicarinatus Lee, Proc. Phil. Acad. Nat. Sci., VI, 



1852, 44. 

 Elongate, subcylindrical. Dull black ; thorax tinged with bronze ; ely- 

 tra each with a- rather broad yellow stripe extending from humerus seven- 

 eighths to apex; tarsi and antennae reddish-brown. Thorax with the sides 

 parallel in front of and behind the middle, scarcely broader at base than 

 apex ; the dorsal channel and an oblique groove each side distinct. Second 

 elytral interval distinctly but feebly carinate near base, the fifth carinate 

 its full length ; striaa rather deeply and coarsely punctured on base, more 

 faintly near apex. Length 3.5—4 mm. 



Spencer County; rare. June 13. Described from Ohio. 



1301 ( ). Stenelmis sdlcatus, sp nov. 



Broader, more robust and less convex than Moarinatus. Deep black; 

 elytra each with an oblong yellow spot behind humerus and a more elon- 

 gate one on apical third ; antennae and tarsi reddish-brown. Thorax finely 

 and sparsely granulate and with a deep median groove extending from 

 base three-fourths to apex, the sides of groove convergent near base; disk 

 also with two oblong oblique tubercles each side of groove, the hind one 

 separated from the latter by an oblique depression. Elytra with second 

 interval elevated on basal third, fifth carinate its full length ; striae coarsely, 

 shallowly and rather closely punctate. Length 3.5 mm. 



Lake Maxinkuckee, Marshall County; frequent. October 26. 

 Specimens were sent me by H. Walton Clark, of the U. S. Fish Com- 

 mission, who reported it as "apparently spending its life in the 

 intervals of the marlj^ growth on mussels, etc., at the bottom of the 

 lake, and can usually be procured in numbers by examining the 

 concretions of marl." From the descriptions I at first thought it 

 to be qiiadrimac'iilahis Horn, but comparison with cotypes of the 

 latter at Cambridge, shows the sculpture of thorax to be wholly 

 different. Several unnamed specimens of sulcatus from New York 

 were in the Cambridge collection. 



