TROPISTERNUS. 55 
tion, extending from the north of the United States to Uruguay. About thirty-five 
species are known: of this number five are peculiar to America north of Mexico, two 
are common to North America and more southern regions, South America has fourteen 
or fifteen species, and two or three are known from the Antilles. 
1. Tropisternus collaris. 
Hydrophilus collaris, Faby. Syst. Ent. p. 229°. 
Tropisternus collaris, Cast. Hist. Nat. ii. p. 54). 
Hab. Mexico (coll. Sawnders); Panama.—ANTILLES, St. Domingo ; SoutH AMERICA, 
from Caraccas to Entre Rios, Brazil 2. 
2. Tropisternus mexicanus. (Tab. II. fig. 3.) 
Tropisternus mexicanus, Cast. Hist. Nat. ii. p. 54°. 
Hab. Merxico!, Jalapa, Oaxaca (Hoge), Vera Cruz (Sallé); Guaremaa, Cubilguitz, 
Paso Antonio 400 feet (Champion); Nicaragua, Chontales (Belt & Janson). 
Although very closely allied to the South-American 7. collaris, I believe, from the 
examination of a large number of specimens of both species, that T. mexicanus is truly 
distinct. It has seven green lines on each wing-case (including a sutural one) separated 
by very narrow yellow spaces; while in 7. collaris there are five such lines; and in this 
latter species the second and fourth yellow interstices are filled behind by short green 
lines which connect, by overlapping, with the extremities of the adjacent green lines, 
which are more or less abbreviated. The Mexican insect has likewise less powerful hind 
legs. The green mark on the middle of the thorax is but little variable in its extent, 
but it is generally rendered more or less indistinct by being surrounded with a cloud of 
dark colour of very variable size ; and it is to such individuals that Castelnau’s description 
refers. 
A specimen from Vera Cruz is figured. 
3. Tropisternus apicipalpis. (‘Tab. II. fig. 2.) 
Hydrophilus apicipalpis, Chevy. Col. Mex. fasc. 3°. 
Tropisternus apicipalpis, Cast. Hist. Nat. ii. p. 53°. 
Hab. Mexico, Jalapa (Hoge), Tuxtla and Vera Cruz? (Sallé); Nicaracua, Chontales 
(Belt) ; Costa Rica (van Patten). | 
A Jalapa specimen is figured. 
4. Tropisternus chalybeus. 
Tropisternus chalybeus, Cast. Hist. Nat. ii. 53°. 
Hab. Mexico, Oaxaca (Hoge), Tuxtla, San Andres (Sallé); Nicaragua, Chontales 
(Belt); Panama.—AnvILLEs, Guadaloupe, Brazil 4. 
