On Aquatic Carmvorous Coleoptera or Dytisade. 643 
997. Dytiscus vexatus, n. sp.—Subtus testaceus, metasterno late nigricante, seg- 
mentis ventralibus parum nigro-marginatis, supra piceus, prothorace limbo omni 
elytrisque flavo-marginatis, antennis pedibusque rufis, prosterni processu lato, brevi : 
coxarum processubus apicibus breviter prolongatis, angustatis et acuminatis ; sutura 
frontali profunda. Long. 29, lat. 15 m.m. 
The clothing of the male tarsi is similar to that of D. cireumcinctus. I have seen 
only a single male ; it is allied to D. cireumcinctus, 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 in form are just a trifle less 
elongate, and the frontal suture is deeper; the undersurface is also rather more 
marked with black. Irom D. dauricus, the species differs by the shorter coxal 
processes, smaller size, and some less important details. 
North-Western North America. 946. 
998. Dytiscus dauricus, Gebl., M.C.—Subtus testaceus, conspicue nigro-variegatus, 
supra niger, prothorace limbo omni elytrisque flavo-marginatis, antennis pedibus- 
que rufis ; prosterni processu lato, haud elongato ; coxarum processubus evidenter 
prolongatis, angustatis et acuminatis: sutura frontali (preesertim in femina) profunda. 
Long 82, lat. 16 m.m. 
Mas, nitidus, elytris ad apicem sat punctatis. 
Fem. (a), subopaca, elytris ad basin ultra medium sulcatis, ad apicein crebrius 
fortiterque punctatis ; protnorace undique crebrius fere dense punctato. 
(b), nitida, prothorace subopaco, subtiliter crebre punctato, elytris ad apicem sat 
crebre et fortiter punctatis. 
The palettes of the male tarsi are formed as in D. cireumcinctus. 
The species is intermediate in most respects between D. circumcinctus, and 
circumflexus ; 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. circumflexus 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. diffinis, Lec., 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 ; Angara River). 947. 
TRANS. ROY. DUB. SOC., N.S., VOL. II. 40 
