﻿19^-)% 55" 

 553. 

 GERRIS APICALIS. 



Order Hemiptera. Fam. Hydrometidse. 



Tyj)e of the Genus, Cimex lacustris Linn. 

 Gerris Lat., Guild., Curt. — Hydrometra Fab. — Aquarius Schel.— 

 Cimex Linn., DeG. 



Antenna inserted before the eyes on each side the nasus, as long 

 as the head and thorax, filiform, 5-jointed, basal joint the longest 

 and a little curved, 2nd and 4th shorter of equal length, 3rd 

 minute, 5th longer than the 2nd (4). 



Labrum short, dilated and ciliated at the base, terminating in an 

 elongated attenuated and pointed lobe, transversely striated (3). 

 Mandibles and Maxillte long slender and capillary, inclosed in the 

 Labium which is longer than the head, rather stout pubescent 

 and 4-jointed, basal joint somewhat cup-shaped, 2nd rather 

 smaller, 3rd long and attenuated, 4th short slender and pointed 

 (2). 

 Head porrected, oblong, rather narrow and elongated, the apex produced 

 and rounded, leaviny shoulders for the attachment of the antenna : 

 eyes globose and very prominent (1, the head in profile). Thorax 

 oblong, truncated before, ovate behind; scutellum invisible : Abdo- 

 men linear in the male, slightly ventricose in the female, the sides 

 reflexed, the antepenultimate joint spined on each side, the '2 follow- 

 ing joints narrowed, the apical one conical, especially in the female. 

 Elytra and wings incumbent, the former coriaceous and covering the 

 back with 5 strong longitudinal nervures ; the latter membranous 

 with very few nervures. Legs attached laterally, anterior raptorious, 

 the shortest and stoutest, the others long and slender, intermediate 

 the longest : thighs simple, longer than the tibia except in the anterior 

 pair : tarsi biarticulate, the basal joint long, except in the anterior : 

 claws curved inserted beneath the apex of the tarsi which projects 

 over them (6, afore leg). 



Apicalis. — Curtis's Guide, Gen. 1080. n. 6. 



Black, silvery beneath; a long spot on the fore part of the 

 thorax and a line on each side ochreous ; margins of abdomen 

 and apex beneath of the same colour ; the lateral spines very 

 short ; underside of legs dull ochreous, tips of thighs and tibise 

 and the tarsi brovni, anterior with a spot at the base and apex 

 only of the thighs ochreous : a hne on the interior margin at the 

 base of the elytra and the wings pearly white, apical portion of 

 the latter brown. 



In the Cabinets of Mr . Dale and the Author. 



These insects by rowing with their posterior feet ghde over 

 the water with great swiftness, and their undersides are ren- 

 dered impervious by the beautiful silvery hairs with which 

 they are densely covered. Gerris is most nearly allied to 

 Velia (pi. 2), but is distinguished by its horizontal head, the 

 great length of the 4 posterior legs, which are very remote 

 from the anterior, and the tarsi are biarticulate. Like Velia 

 and Hydrometra, some adult specimens are apterous, as in 

 G. Paiisari'jis which is very like G. paludwn, but I cannot 



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