﻿downward, watching probably for their prey ; and upon the least 

 alarm they row off' and dive with the greatest celerity, their hinder 

 lej^s (which are most beautifully fringed with long silky hair) serving 

 (liem like oars, from whence the appellation of Boatfly. 



The genus Notonecta contains 3 species, differing only in colour 

 and markings. 



1. N. furcata Fah. Ent. Syst. 4. 58. 2.— Don. IG. 560. 2.— Sam. pi 5./. 3. 



Length 7'z lines. Oclireous, eyes piceous ; head and thorax shining: 

 scutellum metathorax and al)domen black, the latter with the margins 

 ochreous-yellow : elytra brown with 2 broad pale ochre streaks at the 

 base ; a spot at the middle ochreous brown, edge of costa and apex pale 

 fuscous variegated with brown : wings opalescent, with a slight yellowish 

 tint, nervures piceous. 



This species is less abundant than the next, but may be found 

 plentifully round London and other parts of the kingdom, from 

 April to October. Mr. Dale has observed it at Glanville's Woot- 

 tou ; Isle of Portland ; and New Forest. 



2. N. glauca Linn. Faun. Suec. 244. 903. — Don. 3. 75. 



Length 6\ lines. Ochreous, eyes piceous ; head and thorax shining, the 

 basal half of the former more or less lead-coloured : scutellum metathorax 

 and abdomen black, the apex and sides of the latter ochreous : elytra 

 with the costa ferruginous, bearing several blackish spots, and frequently 

 a brown spot on the inferior margin ; posterior margin semitransparent, 

 the tip brownish : wings opalescent, with a slight yellowish tint, nervures 

 ochreous. Sometimes the elytra are slightly sprinkled with brown spots 

 on the inferior margin. 



Found in almost every pond from the middle of March to the 

 end of October. 



3. N. maculata Fah.— Curt. Brit. Eiit.pl. 10.— Don. 16. 560. 1. 



Ochreous : eyes piceous ; head and thorax shining, the latter inclining to 

 cinereous behind ; metathorax bright orange, black at the base as well as 

 the scutellum : abdomen orange, with a semiorbicular velvety black patch 

 at the base, lateral margin of the penultimate joint green : elytra orange- 

 ochre, irregularly clouded and spotted with brown, posterior margin pale 

 brown : wings opalescent, with a yellowish tint, orange at the base, the 

 nervures brownish : legs sometimes greenish-ochre. 



This beautiful insect is rarely found near London, but it has 

 occurred at Turnham Green ; in the West of England it is more 

 abundant, and is found from the end of July to llie beginning of 

 October. jNIr. Dale first met with it at Glanville's Wootton ; after- 

 wards in the New Forest; Isle of Portland; on C'licddcr Cliffs in a 

 pond free from weeds, and in .Scotland; at Charniouth; near Bath; 

 also near Bristol, and in the neighbourhood of Exeter and Ply- 

 mouth, by Dr. Leach. 



A Notonecta allied to macnlala, and discovered by the late ^Ir. 

 II. Scales, is mentioned in the Entomological Transactions, which 

 Mr. Dale says may be only a variety of >V. glauca, which lie has 

 found to vary consiilerably, especially at W'hittlesea Mere. 



Ccrastiwn aqiiaticum (Marsh Mouse-ear) is figured in the plate. 



