CLASS V. INSECTA. 



159 



Sp. 1. Hi/d. Hi^biirri Black; front and margin of the thorax fernigine- 



ous, margins of the elytra yellow with black spots, 

 Dytiscus parapleurus. Marsh. 

 Inhabits ponds : is of rare occurrence near London. 



Genus 62. ACILIUS. Leach's ZuoL Misc. vol. iii. 

 External rnaxillari/ palpi with the second joint obconic, third elongate 



obconic, fourth longer, nearly cylindrical, and rounded at its apex. 



Anterior tarsi of the male patelliform : el^/tra of the female sulcated. 

 Sp. 1. Ac. sulcatus. 

 Dytiscus sulcatus of authors. 

 Inhabits ponds and stagnant waters, and is very common. 



Genus 63. DYTICUS. Geoff., Illig., Leach. Dytiscus. Linni, 

 Fahr., Latr., Marsh. 



External marillajy palpi with the third and following joint of equal 

 lengtli; the last gradually increasing from the middle : anterior tarsi 

 of the male patelliform : {PI. 3. Jig. 13. a.) e/i/tra of the female sul- 

 cated. 



Sp. 1. Dyt. marginalis. Ovate, olive-black above, luteous red beneath ; 

 the scutcllum of the same colour with the elytra : clypeus, whole 

 margin of the thorax, and border of the elytra, red clay-colour; bi- 

 furcature of the sternum lanceolate. {PL 3. ftg. 13. c.) 



Inhabits Europe. In Britain it is common in ponds at all seasons of 

 the year. 



Dytiscus circumflexus of Fabricius is abundant in the ponds near 

 London. It is distinguished from marginalis by its more elongate 

 shape, by the bifurcate process of the sternum being spine-shapetl, 

 and by the colour of the scutellum, which is invariably ferruginous. 

 {PI. 3. fig. 13. b. sternum.) 



Fam. IV. Gyrinid^:. Leach. 



Internal maxillary palpi composed of one part: arifenna: very short: 

 eyes divided so as to appear as four : four hinder feet compressed, fo- 

 liaceous, formed for swimming. 



Genus 64. GYRINUS. Linn., Fahr , Latr., Gyll, Leach. 

 " * Elytra naked, with punctured striaJ' Leach. 

 Sp. 1. Gyr. Natator. Oval: elytra with punctured stris ; the inflex<-d 

 margin testaceous. {PI. 2.fg. 2. a. antenna magnified, b. the hinder 

 leg magnified.) 

 Inhabits stagnant ^vaters. 



" ** Elytra smooth, lillose.^' Leacii. 

 Sp. 2. Gyr. villosus. Fabr., Gyll. 

 Gyrinus Moderii. Marsham. 

 Inhabits rivers and running waters. 



