410 INSECTA. 



COLYMBETES, CluirV. 



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 antennae, 

 at least the length of the head and thorax. The body is perfectly 

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

 very slightly so * (a). 



HyoROBiA, Lat. — Hydrachna, Fab. Clairv. — Pcelobius, Schcenh. 

 The tarsi also composed of five distinct joints, the four anterior of 

 which are almost equally dilated at base, in the males, into a little 

 palette forming a long square ; but the antennae are shorter than the 

 head and thorax ; the body is ovoid and very thick in the middle ; eyes 

 prominent f . 



Hydroporus, Clairv. — Hyphydrus, Schcenh. 



The four anterior tarsi nearly similar, and spongy tmderneath, in 

 both sexes, composed of but four distinct joints, the fifth being 

 deficient or very small and concealed, as well as a part of the last, in 

 a deep cleft in the third. 



These Insects have no apparent scutellum X (h). 



aciculatus, lb. Ill, 30 ; — D. leerigutus, lb. 23 ; — D. tripunctatus, lb. 24 ; — D. ntficol- 

 lis, lb., II, 20 ; — D. vittatiis, lb., I, 5 ; — D. griseus, lb., II, 12 ; — D. sticficus, lb., 

 11,11; — D. circumjfexus, Fab. Of American species the D. ^w6no/a/«s, verticalis, 

 medialus, ianiolis, &c. 



* D. fuscus, Panz., Faun. Insect. Germ., LXXXVI, 5; — D. cinereus, Fab.; 

 Panz., lb., XXXI, 2 ;— D. zonatus, Fab. ; Panz., lb., XXXVIII, 3 ;— D. hipuncta- 

 tits, Fab.; Panz., lb., XCI, 6 ;—D.fenestratus, Fab. ; Panz., lb., XXXVIII, 16 ; 

 D. chalconatus, Fab. ; Panz., lb., 17 ; — D. ater. Fab. ; Panz. lb., 15 ; — D.gutfatus, 

 Payk. ; Panz., lb., XC, 1 ;— D. ftiUyinosus, Fab. ; Panz., lb., XXXVIII, 14 ;— 

 D. bipustulatus, Fab. ; Panz., lb., CI, 2 ; — D. stagnalis, Fab. ; Panz., lb., XCI, 

 7 ; — D. transversalis, Fab. ; Panz., lb., LXXXVI, 6 ; — D. ahbreviatus, Fab. ; Panz., 

 lb., XIV, 1 ; — D. maculatus, Fab. ; Panz., lb., 7 ; — D. agilis, Fab. ; Panz., lb., 

 XC, 2 i—D. adspersiis, Fab. ; Panz., lb., XXXVIII, 18 ;— Z). minuius, Fab. ; Panz., 

 XXVI, 3, 5 ;— Z>. Leander, Oliv., lb.. Ill, 25 ;— £>. variiis, Oliv., lb., II, 17 ;— 

 D. himaculatits, Oliv., lb., 18. See Clairv., Entom. Helvet. II, genus Cuhjmhetes. 



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

 tarsi of the males are but slightly dilated, compose the genus Lacophilus of Leach, 

 •who cites the following : — D. hyalinus, Marsh ; — D. inlerrupfus, Panz. ? — D, minutus, 

 L. ; — D. murmoreus, Oliv. See his Zool. Miscell. Ill, p. 72. 



t Hydrachna Ilermanni, Fab. ; Lat. Gener. Crust, et Insect., I, vi, 5 ; Clairv., 

 Entom. Helv. II, xxvii, A, a ; — H. uUginosa, Clairv., lb., B, b. 



These Insects -with the Halipli, in the system of Leach — Zool. Miscell. p. 68 — 

 form a particular group, the characters of which are : a scutellum ; all the legs 

 adapted for walking, with five joints to all the tarsi and two terminal hooks to the 

 last. 



The Hygrobiae have their exterior palpi somewhat enlarged at the end ; two stout 

 and approximated spurs at the extremity of the tibiae, and their anterior tarsi sus- 

 ceptible of being doubled under the tibise to which they are annexed. 



J In the preceding divisions, some small species excepted, it is very apparent. 



<^ (a) Add to the species of Colymbetes the C. enjthropterus, fenestralis, ambi- 

 guus, seriatus, nitidus, bicarinatus, venustus, glyphicus, obtusatus, &c. Of the G. La- 

 cophilus the L. macidosus and proximus. — Eng. Ed. 



{b) Add of American species the Hydrop. imdidatm, oppotitWf niger, catoscopiwn, 

 iacvstris, pamlkhSf xmMatHs, &c.—- Eng. Ed. 



