212 LAKE SUPERIOR. 







HALIPLUS Lair. ^diffinis. 



americanus Aube', 21. * fasciventris Say. Exp. 2, 270. 



^borealis. carolinus Aube', 120. 



longulus. verticalis Say. Am. Tr. 2, 92. 



83 nitens. ACILIUS Leach. 



83 cribrarius. fraternus Harris. N. E. Farmer. 

 DXTISCUS Linne. semisulcatus Aube. 



confluentus (confluens) Say. Am. Tr. HYDATICUS Leach. 



4, 440. liberus. 



Oolifjbuk'd Kb. N. Z. 75. Dytiscus liberus Say. J. Ac. 5, 160. 



84 Cordieri Aube', 108. H. brunnipennis Aube, 203. 

 Harrisii Kb. N. Z. 76. nigricollis Kb. N. Z. 73. 



32 H. borealis. Ovalis, rufo-testaceus nitidus, thorace punctate, elytris apice oblique 

 truncatis, sutura acuminata, valde punctato-striata, interstitiis sparsim uniseriatim 

 punctulatis ; basi anguste, sutura, apice maculisque utrinque 5 nigris. Long. -12. 



One half larger than H. americanus, and easily known by the want of the basal striola 

 of the thorax ; the base of the elytra is blackened along the edge : the spots placed as 

 in H. americanus. 



33 H. nitens. Ovalis convexus, pallidus pernitidus, capite postice, thorace antice nigro- 

 maculatis, hoc densius punctato (grossius ad basin) ante basin transversim leviter im- 

 presso, lacvigatoque, elytris valde punctato-striatis, interstitiis uniseriatim punctatis, 

 sutura angustissime, apice, guttisque utrinque 6 minutis nigris. Long. -15. 



Head finely punctured, with a smooth vertical space. Elytra slightly, but not suddenly 

 dilated behind the thorax, then regularly narrowed to the tip, which is obliquely trun- 

 cate and acuminate : the disc is marked with two spots at the anterior third placed 

 obliquely forward and outwards, just behind the middle 2 or 3 nearly transversely, and 

 2 or 3 more obliquely backwards and outwards at the posterior fourth. Varies, with the 

 posterior spots wanting. St. Ignace. 



33 H. cribrarius. Ovalis convexus, pallide testaceus, capite postice, thorace antice 

 nigro-maculatis, hoc apice bisinuato, densius punctato, basi grosse sparse punctato, 

 punctis transversim sub-biseriatim digestis, elytris grosse punctato-striatis, interstitiis 

 uniseriatim punctatis, sutura angustissime, apice guttisque 6 vel 7 parvis nigris. 

 Long. -17. 



Very similar to the preceding, but the points above and beneath are larger. The 

 elytra are less attenuated behind the dilated part, the sides being nearly parallel. 



34 I found the elytra of a ? , and have seen perfect specimens from Lake Huron. 

 It is smaller than D. Harrisii, the oblique yellow band at the tip of the elytra is very 

 distinct, the sulci terminate at \ from the apex, and are not confluent. In the latter 

 species the 9 has smooth elytra. 



35 D. diffinis. Elongato-ellipticus antice vix angustatus, supra nigro-olivaceus 

 nitidus, labro clypeo capitis macula angulata, thoracis margine toto, elytrorum lateribus, 

 corporeque subtus toto testaceis, abdomine utrinque vix infuscato ; lobis metasterni 

 postice divergentibus, apice acute rotundatis. Long. 1 - 15, lat. '61. 



$ elytris 3-seriatim punctatis, punctis pone medium paucis dispersis. 



Eagle Harbor. Mr. Rathvon. Form of confluens, but only one half the size. The 

 sides of the thorax scarcely rounded, the posterior yellow margin scarcely wider in the 

 middle than at the angles. 



36 Varies with the posterior margin of the thorax, narrowly testaceous. 



