COLEOPTERA. 323 



rower, or more oval and more depressed than the preceding 

 ones; exterior margin of the thorax and elytra yellowish; the 

 latter finely striated in the female. Environs of Paris, and Ger- 

 many. 



D. serricornis, Payk., Nov. Acad. Sc. Stock., XX, i, 3. Re- 

 markable for the anomalous form of the antennae of the male, 

 the four last joints of which form a compressed and serrated 

 mass(l). 



Colymbetes, Clairv. 



All the tarsi composed of five very distinct joints; but the four 

 anterior, in the males, have the three first equally dilated, constitut- 

 ing, collectively, a small palette forming a long square; the anten- 

 nae, at least the length of the head and thorax. The body is per- 

 fectly oval, and wider than it is high; the eyes are not protuberant, 

 or but very slightly so(2). 



(1) Doctor Leach has established his genus Agabus Zool. Miscel. Ill, p. 69 

 and 72 on this character. Certain slight differences in the form and relative 

 proportions of the joints of the exterior maxillary palpi have also induced him to 

 establish some others, such as Htdaticus (D. Hybneri, transver sails, stagnalis, 

 4-vittat/us) : Acinus (D. sukatus): and Trogus (D. lateralis). The last is the only 

 one that can be retained on account of some other characters. The tibise of the 

 posterior legs are short and very wide, and the tarsi are only terminated by a 

 single hook. 



To the species above quoted add D. sukatus, Fab.; Clair., Entom. Helv., II, 

 xx; D. costalis, Oliv. Col. Ill, 40, 1, 7; D. punctaius, lb. I, 6, b and I, e-D. 

 aciculatus, lb. Ill, 30; D. Isevigatus, lb., 23; D. tripuncfatas, lb. 24; D. rufi- 

 collis, lb. II, 20; D. vittatus, lb. I, 5; D. griseus, lb., II, 12; D. sticticus, lb. II, 

 H; D. circumflexus, Fab. [Of American species the B. fimbriulatus, verticalis, 

 mediatus, tseniolis, &c. Am. Ed.] 



(2) B. fuscus, Panz., Faun. Insect. Germ., LXXXVI, 5; B. cinereus, Fab.; 

 Panz. lb., XXXI, 2; B zonatus, Fab.; Panz., lb., XXXVIII, 3; B. bipunctatus, 

 Fab.; Panz., lb., XCI, 6; 7). fenestratus, Fab.; Panz. lb. XXXVIII, 16; D. chal- 

 conatus, Fab.; Panz. lb. 17; B. ater, Ffb. Panz. lb., 15; B. guttatus, Payk.; 

 Panz., lb., XC, l-B.fuliginosus, Fab.; Panz., lb., XXXVIII, U;B. bipustula- 

 tus, Fab.; Panz., lb., CI, 2; D. stagnalis, Fab.; Panz., lb. XCI, 7; D. transver. 

 salis, Fab.; Panz., lb., LXXXVI, 6; I). abbreviatus, Fab. Panz. lb. XIV, 1; 

 I), maculatus, Fab.; Panz., lb., 7;D. agilis, Fab.; Panz., lb. XC, 2; D. adsper- 

 sus, Fab.; Panz., lb., XXXVIII, 18; I), minutus, Fab.; Panz., XXVI, 3, 5;D. 

 Leander, Oliv., lb. Ill, 25; D. varius, Oliv., lb. II, 17; D. bimaculatus, Oliv., lb. 

 18. See Clairv,, Entom. Helvet. II, genus' Colymbetes. 



Certain small species without any distinct scutellum, and in which the anterior 

 tarsi of the males are but slightly dilated, compose the genus Lacophihts of 

 Leach, who cites the following: D. hyalinus, Marsh; D. interruptus, Panz. > D. 

 minutui, L.; D. marmoreus, Oliv. See his Zool. Miscell. Ill, p. 72. 



