DYTICIDiE. — DYTICUS. 87 



sitions to the Zoological Club of the Linnean Society *, three species 

 alone were to be found in our cabinets, or had been recorded to 

 inhabit Britain ; the number has since been nearly trebled. Exclu- 

 sively of their large size, which exceeds that of the other aquatics, 

 excepting Hydrous piceus, they may be known from the rest of the 

 family by the nearly equal length of the three terminal joints of 

 the external maxillary palpi, and the oblique truncation of the last; 

 the elongation of the first, and the brevity of the second, joint of 

 the antennae. The genus evidently contains several dissimilar forms, 

 but as they are not readily discriminated without characters drawn 

 from the disparities of sex, which are decidedly bad, I shall merely 

 observe, that in the two first species both sexes have smooth elytra, 

 in the remainder the females have them sulcated; again, the three first 

 species are distinguished by considerable discrepancy in the size of 

 the anterior claws in the respective sexes : the form of the furcate 

 apex of the sternum differs according to the respective species. 



A. With the margin of the elytra not dilated. 



Sp. 1. conforrais? Olivaceo-nigricans, subtus testaceus, suturis pectoris nigris, 

 thoracis limbo vittdque elytrorum marginali luteis, elytris posterius latioribus, 

 sterni laciniis lanceolato-acuminatis. (Long. corp. 1 unc. 4 lin.) 



Dy. conformis ? Kunze. — Steph. Coital, p. 52. No. 524. 



Olive-black, the elytra throughout finely punctulated, and dilated as in Dy. 

 marginalis : head impunctate, with the mouth and labrum dull ferruginous, 

 and an obsolete triangular rufous spot on the forehead : thorax finely punctu- 

 lated, the hinder margin sinuated, the anterior with an interrupted row of 

 impressed dots, and all bordered with luteous, the sides most deeply so ; the 

 disc with a longitudinal line : elytra with three rows of impressed dots, the 

 spaces between punctulated, especially towards the apex, the lateral margin 

 yellow at the base to a little beyond the middle: body deep testaceous or 

 yellow beneath, the sutures of the breast, and some fasciae at the base of the 

 abdomen, black; the laciniae of the sternum lanceolate-acuminate: legs pale 

 testaceous ; claws black. Female similar, with very obsolete rudiments of sulci. 



This species has been taken in Devonshire, near Ipswich, and, 

 I believe, in Cambridgeshire. " Whittlesea Mere, once taken." — 

 Mr. Chant. 



Sp. 2. circumcinctus. Plate XII. f. 6. — Subolivaceo-niger, subtus testaceus, 

 immaculatus, thoracis limbo inoequaliter elytrorumque margine luteis, elytris 

 serie punctorum inter singulas strias ordinarias, sterni luciniis acutis. (Long, 

 corp. 1 unc. 3—4 lin.) 



Dy. circumcinctus. Abrens.— Steph. Catal. p. 52. No. 523. 



* See Zoological Journal, vol. ii. p. 550. 



