AQUATIC COLEOPTERA. 117 
9. Laccophilus cayennensis Aubé. Entre Rios, Santa Cruz. 
M. van Volxem's specimens represent two varieties, one agreeing 
with the type in Dejean’s collection mentioned by Aubé, while 
the other is almost without marks on the upper surface. 
10. Hydrocanthus lævigatus (Brullé) Aubé. Santa Cruz, a 
single individual. 
11. Hydrocanthus sp. ? A single individual of a Hydrocanthus 
found at Entre Rios, differs from any species as yet known to me, 
and is perhaps a new species. 
12. Coptotomma argentina Reiche. Buenos Ayres, a single 
individual. 
13. Celina aculeata Aubé. Santa Cruz, 10 to 17. 10. 72, a 
single individual. 
14. Hyphydrus n. sp. À single specimen from Santa Cruz 
agrees with specimens I have received from Rio Janeiro: the spe- 
cies will be described in my Revision of the family. 
15. Vatellus lentus Dej. Santa Cruz. 
GYRINIDÆ. 
1. Enhydrus sulcatus Wied. Botafogo, a single indivi- 
dual. 
2. Gyretes dorsalis Aubé. Santa Cruz. 
d. —  cinctus Germ. Rio Janeiro, one individual. 
4. Gyrinus apicalis n. sp. Ovatus, convexus, haud elongatus, 
sat latus, supra œneo-chalybeus, marginibus æneis ; sublus fer- 
rugineus, prothoracis, elytrorum lateribus pedibusque testaceis ; 
elytris ad latera subtililer strialo-punctalis, interne lævigatis, 
angulis externis rotundatis, margine apicali marginatlo. Long. 
9 mm. lat. 2 2/3 mm. 
Above of a steel colour strongly tinctured with brassy; this 
æneous tinge is very conspicuous at the sides of the elytra, so that 
there there is no appearance of the steel {colour ; the elytra at the 
sides bear rows of fine punctures, of which even the external ones 
become obsolete before the apex, and the seventh row from the 
outer margin is represented only by a few very fine punctures at 
the base, inwards from this the punctures have quite disappeared ; 
the outer apical angle is quite rounded, and the raised lateral 
margin of the elytra, is continued round the apex to the sutural 
angle, which is also rounded, but less broadly so than the outer 
angle. The species is allied to Gyrinus gibbus Aubé. 
Found by M. C. van Volxem at Santa Cruz, 10-17. 7.72. Some 
ANNALES DE LA SOC, ENTOM. DE BELGIQUE, T. XX. 8 
