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Show 32~ INSECTA. ration of a similar period, and the animal is then double its size. Its final length is two inches. They have been observed . summer, to entet· into their pupa state at the end of fifteen da s' to become per."e ct m. sects m. f1i ft een or twenty more. Besidy ' cloaca of the Insects of thi·s f ami'I y, the D ytisci have a tolerabl es crecum, which is perceptible even in the larva. y This great genus is subdivided as follows: Some have antennre composed of eleven distinct joints, the exte. rior pal pi filiform or somewhat larger at the extt·emity, and the base of their posterior feet as well as that of the others exposed. Sometimes the thickness of the antennre gradually diminis~e! from their origin to the extremity; the last joint of the labial i is simply obtuse at the end and unemarginate. Such is Drr1sous, pt·opet·. Where all the tarsi are composed of five very distinct joints which the three first of the two anterior ones are very wide, formlng collectively, a palette, either oval and transverse, or orbicular. ' D. latissimus, L.; Panz. Faun. Insect. Germ. LXXXVI , About an inch and a half long, and easily distinguished by compressed and trenchant dilatation of the exterior margin the elytra, the border of w)lich is yellowish; thorax mar~ne~ all round with the same colour; elytra sulcated and carinate~ in the female. From the department of Vosges in the nortn of Europe and from Germany. D. marginalia, L.; Panz. Ib. 3. About. a fourth smaller; 1 yellowish border all round the thorax, and a line of the same colour on the exterior and non-dilated margin of the elytra; those of the female sulcated from their base to about two-thirds of their length. Fabricius says that if laid on its back, it soon regains its nat· ural position by jumping. Esper preserved a D. marginalia for three years and a half, in perfect health, in a large glass jar. Every week, and som~ times oftener, he threw into the vessel a piece of raw beef about the size of a filbert, on which it darted with great avidity, an~ then completely exhausted its blood by suction. It can go wit~· out food for at least four weeks. It kills the Hydrophilus pi· ceus, although double its own size, by piercing it between t~e head and thorax, the only part of the body that is unarmed. According to Esper, it is affected by atmospheric changes, an~ indicates them by the height at which it remains in the jar. D. Rreselii, Fab.; Rres., Insect., II, Aquat., Class I, ii. Nar· COLEOPTERA. 323 rowe r , Or more oval and more depressed than the pt·.e ceding ones; exterior margin. of the thorax an. d elytra ye.l lowish; the latter finely striated m the female. Environs of Pans, and Ger-m~~ . D. serricornis, Payk., Nov. Acad. Sc. Stock., XX, I, 3. Re-markable for the anomalous form of the antennre of the mal€', 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. collectively, a small palette forming a long square; the anten- ~ . n:e, 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 ve1·~ slightly so(2). (1) Doctor Leach has establish:d hi.s gen~s AoAnus:-Zool. Miscel. III, p .. 69 and 72-on this character. Certam sl1ght differences m the form and relatwe proportions of the joints of the exterior maxillary palpi have also induced him to establish some others, such as IIYDATrcus (D. Hybneri, transversalis, stagnalis, 4-tiltatw): AcxLius (D. sulcatus): and Tnoous (D. latera/is). The last is the only one that can be retained on account of some other characters. The tibire of the posterior legs are short and very wide, and the tarsi are only terminated by a lingle hook. To the species above quoted add D. sulcatus, .Fab.; Clair., Entom. Ilelv., II, u;-D. costalis, Oliv. Col. ITI, 40, 1, 7;-D. punctatus, lb. I, 6, b and I, e;-D. aciculatua, lb. III, 30;-D. lrevigatus, lb., 23;-D. tripunctatus, lb. 24;-D. rufi· rollil, lb. II, 20;-D. vittatus, lb. I, 5;-D. griseus, lb., IT, 12;-D. sticticus, lb. II, 11;-D. circumjlexus, Fab. [Of American species the D. fimbriulatus, verticalis, mtdiatua, tamiolis, &c. .!J.m. Ed.] (2) D. fuscus,'Panz., Faun. lnsect. Germ., LXXXVI, 5;-D. cinereus, Fab.; Panz. lb., XXXI, 2;-D. zonatus, :Fa b.; Panz., lb., XXXVIII, 3 ;-D. bipunctatus, Fab.; Pa11z., lb., XCI, 6;-D.fenestratus, Fab.; Panz. lb. XXXVIII, 16;-D. clwlI! JIIatua, Fab.; Panz. lb. 17;-D. ater, Fr.b. Panz. lb., 15;-D. guttatus, Payk.; Panz., lb., XC, 1;-D.fuliginosus, I~ab.; Panz., lb., XXXVILI, 14;-D. bipustula· IU8, Fab.; Panz., lb., CI, 2;-D. stagnalis, Fab.; Panz., lb. XCI, 7;-D. transveraali8, Fab,; Panz., lb., LXXXVI, 6;-D. abbreviatus, Fab. Panz. lb. XIV, 1;D. maculatus, Fab.; Panz., lb., 7;-D. agilis, Fab.; Panz., Jb. XC, 2;-JJ. ad!JperIU8, Fab.; Panz., lb., XXXVIII, 18;-D. minutus, Fab.; Panz., XXVI, 3, 5;-D. 1~, Oliv., lb. III, 25;-D. varius, Oliv., lb. 11, 17;-D. bimaculatus, OHv., lb. 18. See Clairv., Entom. Ilelvet. IJ, 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 L.t.coPIIIT.Us of Leach, who cites the following: D. hyalinus, Marsh ;-D. interruptus, Panz. ?-D. minutu1, L.;-D. marmoreus, Oliv. See l1is Zoo) . Miscell. liT, P· 72. |