710 On Aquatic Carnirorous Coleoptcru or Dijtiscidce. 



punctuation near the sides, and there are also a few fine punctures scattered over its 

 surface ; the internal claw of the hind feet remains rudimentary and can only be 

 seen at the base and underside of the larger claw. 



The only two specimens I have seen of this species, I obtained from Castlenau's 

 collection ; one of them which is rather larger and broader than the other, was 

 standing side by side with a male of another species, labelled " Cy bister fallax, Aube, 

 dubius Lucz. Cayenn." ; the other was standing alone labelled " Cybister puncticollis, 

 Brulle, Bo. Ayres,' while on the pin was a label, " Bresil, C'ol. Dejean " I am not 

 at all sure that this is really Brulle's C. puncticollis which was found on the Kiver 

 San Miguel, centre of Bolivia. 



South America, (1 Buenos Ayres; ? Cayenne). HOG. 



Group 5. 



1111. Cybister fallax, Aubd, Tragus fallax, M.C. — Ovalis, parumlatus, convexus, 

 nitidu.s, supra olivaceo-niger, capite anterius prothoraceque ad latera testaceis, 

 elytris vitta intramarginali posterius lata sed parum arguta, testacea ; subtus niger 

 pedibus quatuor anterioribvTS rufis, pedibus posterioribus picescentibus ; elytrorum 

 epipleuris parum latis. Long. 27, lat. 15i m.m. 



I have not seen any male of this speeies, the female has no trace of any sexual 

 sculpture. 



The species is readily distinguished from others of this group, by its smaller size 

 and narrower form ; the yellow band on the elytra is broad, at the shoulder it 

 quite touches the lateral margin, aiter that is distinctly sej^arated from it, behind 

 the anterior two-thirds of its length it becomes broader and aarain reaches the 

 margin, though in a somewhat vague manner, just before the extremity it is dilated 

 by joining an agglomeration of small ferruginous dots, and terminates as a point at 

 the suture. 



I have seen only two individuals of this species, one of them, from Dejeau's 

 collection, was there labelled " Trochalus fallax mihi, h. in Cayenne, D. Lacordaire" : 

 the other w^as in Edwin Brown's collection and labelled in his handwriting " Cybis- 

 ter flavocinctus, Chev., Mexico." The determination being wrong it is probable 

 that the locality also of this latter specimen may be erroneous. 



Cayenne.; 1 Mexico. 1107. 



1112. Megadytes obesus, n. sp. — Ovalis, latus, parum elongatus, convexus, supra 

 olivaceo-niger, capite anterius prothoraceque lateribus testaceis, elytris vitta intra- 

 marginali ante apicem evanescente testacea ; subtus niger, pedibus quatuor 



