On Aquatic Candvorous Coleoptera or Dytisadce. 643 



997. Dytiscus vexatns, n. sp. — Subtus testaceus, metasteriio late nigricaute, seg- 

 mentis ventralilius parum nigro-marginatis, supra piceus, prothorace limbo ornni 

 elytrisque flavo-margiiiatis, an tenuis pedibusque rufis, prosterni processu lato, brevi : 

 coxarum processubus apicibus breviter prolongatis, angustatis at acuminatis ; sutura 

 frontali profunda. Long. 29, lat. 15 m.m. 



The clothing of the male tarsi is similar to that of D. circumcinctus. I have seen 

 only a single male ; it is allied to D. circumcinctus, but is smaller than the smallest 

 male I have seen of that species, it is of a more pitchy colour above, the punctuation 

 at the very apex of the wing-cases is greater, the eyes are not bordered with yellow, 

 and the coxal processes though exceedingly similar iu form are just a trme less 

 elongate, and the frontal suture is deeper ; the undersurface is also rather more 

 marked with black. From D. dauricus, the species differs by the shorter coxal 

 processes, smaller size, and some less important details. 



North- Western North America. 9i6. 



998. Dytiscus dauricus, Gebl., M.C. — Subtus testaceus, conspicue iiigro-variegatus, 

 supra niger, prothorace limbo umni elytrisque flavo-marginatis, antennis pedibus- 

 ([Vlq rufis ; prosterni processu lato^ baud elongato ; coxarum processubus evidenter 

 prolongatis, angustatis et acuminatis: sutura frontali (preesertim in femina) profunda. 

 Long 32, lat. 16 m.m. 



Mas, nitidus, elytris ad apicem sat punctatis. 



Fern, (a), subopaca, elytris ad basin ultra medium sulcatis, ad apicem ci'ebrius 

 fortiterque punctatis ; protiiorace undique crebrius fere dense punctate. 



(6), iiitida, prothorace subopaco, subtiliter crebre punctato, elytris ad apicem sat 

 crebre et fortiter punctatis. 



The palettes of the male tarsi are formed as in D. circumcinctus. 



The species is intermediate in most respects between D. circumcinctus, and 

 circurnflexus ; it differs from the former by the greater prolongation of the apices of 

 the coxal processes, by the underside being greatly marked with black, and by the 

 greater thoracic punctuation of the females, while from D. circumfiexus it differs 

 by its rather broader form, less elongate apices of the coxal processes, and 

 shorter prosternal process. The yellow angular mark on the middle of the head 

 generally extends quite forward to join the yellow clypeus. The species seems to 

 vary but little, the Siberian individuals being almost if not quite undistinguishable 

 from the American ones. The species is usually known in collections as D. con- 

 fluens. Say. 



D. difiinis, Lee, is referred to it as a synonym on the authority of Crotch. 



Western North America, and Eastern Siberia. (Kansas, Lake Superior, California, Sitkha ; Lake 

 Baikal ; Transbaikal ; Angai'a River). 947. 



TRANS. BOV. DUB. SOC, N.S., VOL. II. * O 



