GtASS V. INSECT A. 
159 
%>. 1, m,d. Hybneri. Black; front and margin of the thorax ferrugine- 
ous, margins of the elytra yellow with black spots. 
Hytiscus parapleurus. Marsh. 
inhabits ponds: is of rare occurrence near London. 
Genus 62. ACILIUS. Leach’s Zool. Misc. vol. iii. 
External maxillary palpi with the second joint obconic, third elongate 
obconic, fourth longer, nearly cylindrical, and rounded at its apex. 
Anterior tarsi of the male patellifonn : elytra of the female sulcated. 
®p. 1. Ac. sulcatus. 
idytiscus sulcatus of authors. 
Inhabits ponds and stagnant waters, and is very common. 
Genus63. DYTICUS. Geoff., Illig., Leach. Dytiscus. Limit, 
Fabr.y Latr., Marsh. 
External maxillary palpi with the third and following joint of equal 
lenu-th; the last gradually increasing from the middle : anterior tarsi 
of the male patellifonn : {PI. 3. Jig. 13. a.) elytra of the female sul- 
cated. 
Sp. 1 . Di/t. marginalis. Ovate, olive-black above, luteous red beneath ; 
the scutellum of the same colour with the elytra: clypeus, whole 
margin of the thorax, and border of the elytra, red clay-colour; bi- 
furcaturc of the sternum lanceolate. {PI. 3. fig- 13. c.) 
inhabits Europe. In Britain it is common in ponds at all seasons of 
the year. 
Dytiscus circumjlexus oi Eabricius is abundant in the ponds near 
London. It is distinguished from marginaUs by its more elongate 
shape, by the bifurcate process of the sternum being spine-shaped, 
and by the colour of the scutellum, which is invariably ferruginous.' 
{PI. 3. fig. 13. b. sternum.) 
Fam. IV. OyiuniD/E. Leach. 
internal maxillary palpi composed of one part: antenna very short: 
eyes divided so as to appear as four: four hinder feet compressed, fo- 
liaceous, formed for swimming. 
Genus 04. GYR1NUS. Tina.., Fa.hr , Latr., Gyll., I^ach. 
“ * Elytra naked, with punctured stria.” Leach. 
®P. 1. Gyr. Nutator. Oval: elytra with punctured striae; the indexed 
margin testaceous. {PI. 2. fig- 2. a. antenna magnified, b. the hinder 
leg magnified.) 
Inhabits stagnant waters. 
« ** Elytra smooth, villose.” Leach. d 
j’P- -• Gyr. villosus. Fabr., Gyll. 
j yrinus Moderii. Marsham. 
inhabits rivers and running waters. 
