44 ADEPHAGA. 
1. Thermonectes nigro-fasciatus. (Tab. I. fig. 12.) 
Acilius nigro-fasciatus, Aubé, Spec. Gén. vi. p. 186; Sharp, Trans. Roy. Dubl. Soe. n. s. ii. p. 677. 
Hab. Mexico, Puebla, Parada (Sal/é), Guanajuato (Dugés, coll. Sallé), city of Mexico 
(Flohr), San Luis Potosi (Dr. Palmer), Oaxaca (Hoge). 
A considerable series of this species exhibits but little variation. The black fascia 
of the wing-cases is sometimes a good deal diminished in extent ; and the anterior of 
the transverse black marks on the thorax is, though rarely, smaller and broken up. 
The sexual sculpture on the elytra of the female varies much in its extent; but the 
thoracic sculpture seems but little variable. 
2. Thermonectes ornaticollis. 
Acilius ornaticollis, Aubé, Spec. Gén. vi. p. 140; Sharp, Trans. Roy. Dubl. Soc. n.s. i. p. 678. 
Hab. Nortn America, Texas.—MeExico, Cordova (Sal/é), Tehuantepec (coll. Fry). 
The Mexican individuals of this species are referable to two very distinct varieties :— 
Ist, a dark form as described by Aubé (loc. sup. cit.) ; and, 2nd, a variety, of which the 
size is smaller and the black colour of the upper surface is much reduced—the marks 
on the thorax consisting of two scarcely perceptible spots on the middle of the front 
margin, and two elongate marks at the base nearly joined together and each enclosing 
a pale space. 
3. Thermonectes maculatus. 
Acilius maculatus, Aubé, Spec. Gén. vi. p. 142°. 
Hab. Mexico }. 
Although I have not seen any specimen corresponding with Aubé’s description, yet I 
think this insect will prove to be a variety of 7. ornaticollis. 
4. Thermonectes succinctus. 
Acilius succinctus, Aubé, Spec. Gén. vi. p. 145°; Sharp, Trans. Roy. Dubl. Soc. n.s. ii. p. 678. 
Hab. Mexico 1.—Soutnu America, Brazil, Peru. 
5. Thermonectes circumscriptus. 
Dytiscus circumscriptus, Latr. Voy. Humb., Ins. p. 223, pl. xxi. f. 5. 
Acilius circumscriptus, Aubé, Spec. Gén. vi. p. 143; Sharp, Trans. Roy. Dubl. Soe. n. s. ii. p. 679. 
Hab. Mexico, Puebla (Sallé); Guarzmaua, Torola 1000 feet (Champion); Nicaragua, 
Chontales (7. Belt)—Soutu America, from Colombia to Rio de Janeiro; ANTILLEs. 
I have seen only half a dozen specimens from Central America; and they seem to 
indicate it as very variable there. In two of the females found by Mr. Champion at 
Torola there is no sexual sculpture on the thorax; while a specimen found at Chontales 
