CLASS V. INSECTA. 
157 
and when perfect, living on other insects. The anterior and middle 
tarsi in some of the genera have but tour joints. 
A. With a scutellum, feet formed for walking: tarsi, the whole of 
them with Jive joints; claws diductyle. 
Sr HU'S l, — Hinder thighs covered at their base with a shield-shaped plate. 
Genus 51. IIALTPLUS. Lair., GylL, Leach, Cnemidotus. Lllig. 
Hoplitus. Clairv. 
“ * Body oblong oval. Elytra with, elevated ridges .” Leach. 
Labial and external maxillary palpi subulate. 
Sp. 1 . Hal. etevatus. Panz. 
Inhabits running streams. 
“ ** Body oval. Elytra striated.” Leach. 
Sp. 2. Hal. ferrugineus. Linne. 
inhabits ponds and ditches. 
Simps 2 . — Hinder thighs without the shield at their base : .(eyes pro- 
minent.) 
Genus 55. PiELOBIUS. Sclwnlterr, Leach. IIychobia. Latreille. 
IIyoraciin a. Fair. 
External maxillary palpi with the last joint subclavate. 
Sp. 1 . Bal. Herumnni. Black: head, transverse band on the thoiax, 
base and border of the elytra and feet ferrugineous. (PI. 3. fig. 14.) 
Dytiscus Hermanni. Marsh., Oliv. 
Inhabits ponds. The last segment of the abdomen when rubbed 
against the elytra produce a noise. 
B. Scutellum none. Feet, hinder ones, for the most part formed for 
swimming. 
Stiups 3, — The four anterior tarsi with four, the two posterior with 
five joints. 
Genus 56. Hypkydhus. Latr., Gyll., lllig., Schonh., Leach. 
Body nearly globose : the four anterior tarsi with the last joint short ; 
the hinder feet with but one claw. 
8 P- 1. Hyp. oralm. Obscure, ferrugineous, impunctate; the base ot 
the elytra with an impression at the base of the suture, 
dytiscus ovatus. Linne. 
inhabits ponds. 
Genus 57. IIYDRQPORUS. Cluirville, Leach. Hyphydrcs. 
lllig., Schonh., Gyll. 
Eody oval ; the breadth exceeding the height : the four anterior tarsi 
with four joints, {he last joint slender: claws didactyle. 
