740 On Aquatic Carnivorous Coleoptera or Dytiscida;. 



The front and middle tarsi of this species are similar to those of C. confusus ; but 

 the cedeagus presents constant and well marked differences ; its inferior lobe 

 becomes narrower till close to the termination, when it becomes much broader, its 

 exti'emity is broadly emarginate, so that it has a furcate appearance, and is also 

 arched in the transverse direction ; the dorsal lobe terminates in two processes 

 which do not extend to the ajiex, and which diverge from one another before their 

 termination, the apices however are again a little incurved, but not contiguous, 

 being separated in the condition of repose by a broad longitudinal elevation which 

 runs along the middle of the under lobe. The female has a highly developed 

 sexual sculpture, similar to what exists in C confusus, but less distinct on the disc 

 of the thorax, and absent from a rather wider space along the suture of the wing- 

 cases. The epipleuraj of the elytra are flattened and obliquely horizontal, and rather 

 broad, the torsion commences very close to the shoulder, and ceases in a gradual 

 manner about the hind margin of the second ventral segment. 



The species is a rather variable one ; and there may be distinguished three 

 varieties : the first is of short, convex form a good deal narrowed in front, and the 

 sculpture of the female on the thorax and elytra is comparatively less developed, 

 extending on the latter only three-fifths of the length towai'ds the extremity ; this 

 is especially common in northern China and Mantchuria if I may judge correctly 

 from the material before me ; the second form is more elongate, and rather flatter 

 and the sculpture of the female is nearly as largely developed as in C confusus, 

 extending four-fifths or five-sixths of theh" length ; I have individuals of this variety 

 from Shanghai. The third form is broad and robust, and the yellow band of the 

 elytra has a tendency to be prolonged nearer to the suture at the extremity, and 

 the female sculpture is largely developed ; this variety occurs I believe in Southern 

 Hindostan (Madras). In all the variations of this abundant insect the form of the 

 cedeagus remains absolutely without variation ; the varieties in colour, form, &c., 

 already alluded to, merge quite gradually into one another by intermediate specimens. 



Mantchuria, China, Formosa, Southern India. 1088. 



1158. Cybister guerini. Tragus guerini, M.C. — Ovalis, niger, ca2)ite anterius 

 prothoraceque ad latei'a testaceis, elytris vitta intramarginali testacea, ad apicem 

 haud argute hamato-dilatata, suturam hand attingente, pedibus anterioribus et 

 intermediis rufis, femoribus late nigricantibus, tibiis tarsisque intermediis fere nigris. 

 Long. 34, lat. 19^ m.m. 



The male has the front and middle tarsi the same as in C confusus and D. 

 limbatus ; and in the structure of its cedeagus is intermediate between the two ; the 

 female has a highly developed sexual sculpture, the thorax beingentirely covered with 

 irregular scratches, and the elytra bearing elongate longitudinal scratches, these 



