On Aquatic Carnivorous Coleoptera or Dytiscide. 285 
but one individual which is a female; and has the structure of the last ventral 
segment much as in the same sex of M. mareinalis, the front and middle tarsi on 
the other hand are more slender. 
Brazil, (Wehncke). 606. 
89. Macrovatellus ventralis, n. sp.—Oblongo-ovalis, parce pubescens, vix opacus, 
crebre punctatus, fuscus, marginibus minus distincte rufescentibus, antennis pedi- 
busque rufo-obscuris ; capite crebre sequaliter punctato ; prothorace valde transverso, 
lateribus sinuatis, angulis posterioribus acutis, parce punctato, ante basin obsolete 
transversim depresso ; elytris elongatis, deplanatis, minus fortiter et dense punctatis, 
parcius pubescentibus ; coxis posterioribus sat crebre fortiter punctatis. Long. 64 
m.m., lat. 33 m.m. 
The elongate and flattened elytra, the more obscure colour, the less dense and 
less scabrous punctuation of the elytra, and the different punctuation of the head 
characterize this species; the punctures on the head show no diminution on the 
front part. The individual described has lost its tarsi, but is, I think, a male; the 
front femora in the middle are subtuberculate, and near to the prominent part are 
densely ciliate (these characters exist to a slight extent in the other species but 
are more distinct in the present one); the apical ventral segment is remarkably 
short. 
Brazil, (Wehncke). 607. 
I. 12.—Genus VATELLUS. 
Ventral sutures extremely deep ; anterior tarsi extremely elongate and slender. 
The only species known is very rare in collections. 
90. Hydroporus tarsatus, Lap. Vatellus tarsatus M.C.—Oblongo-ovalis, sub- 
tiliter sed evidenter pubescens, dense fortiterque punctatus, opacus, niger, antennis 
pedibusque piceis, femoribus dilutioribus, prothorace transverso, elytris multo 
angustiore, lateribus sinuatis, angulis posterioribus acutis, sat fortiter punctato ; 
elytris densius fortiterque punctatis, scabris ; coxis posterioribus fortiter profundeque 
punctatis ; abdomine sat fortiter punctato, suturis profundis ; tarsis anterioribus, 
elongatis, angustis, articulo 3° quam 2° vix angustiore. Long. 5, lat. 23 m.m. 
The tarsi differ but little in the sexes, but they are not quite so slender in the 
male as in the female ; the hind trochanters in the male are peculiarly globular and 
swollen. 
Cayenne. 443. 
2P2 
