192 KINCAID [37] 



the apical joint of the labial palpi. In most of the European species 

 the labial palpi of the larva are cleft at the apex. 



DYTISCUS DAURICUS Gebler. 

 [Plate XXIII, figs. I and 2.] 



Larva slender, subcylindrical, strongly convex above, flattened be- 

 neath, elongately fusiform ; yellowish white, the head and schlerites 

 mottled with pale brown. Length 50 mm. 



Head rounded, a fifth longer than broad, flattened in front, convex 

 behind ; clypeus broad arcuate, anterior margin with a row of delicate 

 lamellate setae ; frontal sulci shallow, converging behind ; hypostoma 

 deeply excavated ; temples rounded, unarmed ; collar half as wide as 

 head, separated from the latter by a well-marked groove, truncately 

 emarginate above, deeply angularly emarginate beneath ; ventral fur- 

 row of neck broadening anteriorly, basally with a strong median ca- 

 rina, at the extremity of which there is on each side a small rounded 

 eminence. Antennae three-fourths as long as the head, slender seta- 

 ceous, composed of three principal and three small accessory joints ; 

 first principal joint twice as long as third ; second intermediate in 

 length between first and third ; accessory joints successively smaller, 

 the first situated at the base of the antennae, second between the first 

 and second principals, third between the second and third principals. 

 Ocelli six, arranged on the perimeter of a transversely oval convex 

 eminence situated on the sides of the head close behind the antennae ; 

 above each group of ocelli there is a small, but very prominent, shin- 

 ing papilla. Mandibles three-fourths as long as the head, slender, 

 tapering, slightly curved, apex acute. Maxillae longer than the an- 

 tennae ; stipes slender, palpiform cylindrical ; lacinia minute, papilli- 

 form ; maxillary palpi more than twice as long as stipes, composed of 

 three principal and three accessory joints ; the principal joints succes- 

 sively shorter, the accessory joints successively smaller, the first situ- 

 ated between the stipes and first principal joint, the second between 

 the first and second principals, and the third between the second and 

 third principals. Mentum broad, bilobed, emarginate in front ; ligula 

 absent; labial palpi half as long as maxillary palpi, three-jointed, the 

 first joint elongate, slender, the second and third short, subequal. 



Pronotum longer than broad, nearly twice as wide at base as at 

 apex, transversely grooved on each side towards anterior margin ; 

 sides sharply margined, bent downwards and inwards touching the 

 coxa? of the anterior legs; mesonotum and metanotum half as long 



