282 On Aquatic Carnivorous Coleoptera or Dytiscide. 
81. Noterus grandis, Lap. Hydrocanthus grandis, M.C_—Minus latus, convexus, 
pernitidus, piceus, capite thoraceque quam elytris dilutioribus, antennis rufis ; elytris 
pone humeros sinuatis, sublevigatis; spatio inter coxas anteriores minus lato, 
subelevato ; prosterno medio, pectoris coxarumque parte elevata crebre punctatis. 
Long. 7, lat. 83: m.m. 
In the male the apical ventral segment is very little if at all compressed towards 
the apex. 
Africa, (Senegal, Gaboon). 473. 
82. Hydrocanthus deyrollei, n. sp.—Crassus, robustus, latiusculus, sat nitidus, 
niger, antennis rufis, pedibus piceis, elytris seriebus duabus punctorum sat distinctis, et 
versus latera punctis sparsis, lateribus pone humeros, v1x sinuatis ; coxis anterioribus 
late separatis; prosterno, pectore medio laminisque coxarum impunctatis. Long. 
8 m.m. (vix), lat. 43 m.m. 
The male has the hinder part of the apical ventral segment much compressed so 
as to form a ridge terminating in a point. 
Africa, (Gaboon, Brussels Museum ; found I believe by H. Deyrolle). 472. 
II. 4.—Group VaTeEL.int. 
Prosternal process not reaching the metasternum, but terminating in front of and 
between the middle cox; front andmiddle tarsi four jointed, frequently very elongate ; 
outline of body discontinuous at junction of thorax and elytra. Swimming legs slender. 
This group represents in the Dytisci Fragmentati series the Hydroporides of the 
second series. The three genera are South American, and very rare in collections, 
except Derovatellus. 
Ventral sutures very deep, 6 ' : ° . 5 : . VATELLUS, (vide p. 285) 
( Mesosternum very largely visible ;) MACROVATELLUS, 
| size moderate (6-8 m.m. long). (vide below). 
Ventral sutures normal, 
| Mesosternum but little visible ;1 DHEROVATELLUS, 
{size small (4 m.m. long). (vide p. 286). 
I. 11.—Genus MACROVATELLUS. 
Mesosternum largely exposed between the prothorax and metasternum. Outline 
of thorax and elytra very discontinuous. 
The Macrovatelli are moderately large insects (6—8 m.m. long). 
The species* are very similar to one another and extremely rare in collections. 
* Vatellus grandis, Bug. (No. 1,511, huj. op.), from Cayenne is probably another species of the genus. 
