CLASS V. INSEPTA. 157 



and wheii perfect, living on other insects. Tlie anterior and middle 

 tarsi in some of the genera have but four joints. 



A. With a scutellum, feet formed for walking: tarsi, the whole of 



them mith Jive joints; chnvs didacti/lc. 



SriRPS 1. — H<«&?-//(i^As covered at their base with a shield-shaped plate. 



Genus 54. HALIPLUS. Lair., GylL, Leach. Cnemidotus. lUig. 



HoPLiTUS. Ctairv. 



" * Bodij oblong oval. FJj/tra with elevated ridges." Leach. 



Labial and external inaxillary palpi subulate. 

 Sp. 1. Jlul. elevatus. Panz. 

 Inha])its running streams. 



" ** Body oval. Elytra striatedP Leach. 



Sp. "2. TJ(d. frrrugincus. Linne. 

 Inhabits jjonds and ditches. 



Stiups 2. — Hinder thighs without the shield at their base: (eyes pro- 

 minent.) 



Genus 53. PiTi!,LOBIUS. Schonher?; Leach. IIygrobia. Lcdreilk. 



IlyDTvACHNA. Fubr. 

 External inaxillary palpi with the last joint subclavate. 

 Sp. 1. Feel. Herjiianni. Black: head, transverse band on the thoiax, 

 base and border of the elytra aiid feet ferrugineous. {PL 2. Jig. 14.) 

 Dytiscus Ilermanni. JIarsh., Oliv. 



Inhabits j^onds. The last segment of the abdomen when rubbed 

 against the elytra produce a noise. 



B. Scutellum none. Feet, hinder ones, for the most part farmed Jbr 



sicimming. 



Srir.ps 3. — The four anterior tarsi with four, the two pcstei'ior with 

 live joints. 



Genus 56. IIyviiydrus. Latr., Gyll., lUig-, Schonh., Leach. . 

 Body nearly globose : the four anterior tarsi with ihc last joint short; 



the hinder feet witli but one claw. 

 Sp. 1. Hyp. ovatiis. Obscure, ferrugineous, impunctate; the base of 



the el^-tra with an impression at the base of the suture. 

 Dytiscus ovatus. Linne. 

 Inhabits ponds. 



Genus 57. IIYDROPORUS. Clairville, Leach. IlyPHYDRi's. 

 LUig., Sclwnh., Gyll. 

 Body otal ; the breadth exceeding the height : the four anterior tarsi 

 uith four joints, the last joint slender: dazes didactyle. 



