DYTICIDJE. — AGABUS. 83 



I cannot imagine the above insect to be specifically distinct from the foregoing ; 

 its smaller size, deeper colour, and apparent diversity of form, are the only 

 distinctions ; and I have taken both in the same ponds ; but upon the latter 

 subject I shall enlarge at some future period. 



This appears synonymous with the Co. 4-guttatus, De Jean, according to spe- 

 cimens sent by him to Mr. Hope. 



Also taken in the vicinity of the metropolis, in Norfolk, &c. 

 " In Bottisham-fen." — Rev. L. Jenyns. " Sundridge, Kent." — 

 Mr. Ingpen. " Scarce near Kimpton." — Rev. G. T. Rudd. 



f Sp. 40. quadrinotatus. Suboblongo-ovatus, convexus, niger, nitidus, elytris 

 punctis duabus rotundatis albis, antennis rufo-ferrugineis, pedibus nigris. 

 (Long. corp. 4^ lin.) 



Co. 4-notatus mihi. Steph. Catal. Appendix. 



Somewhat oblong-ovate, rather attenuated posteriorly, convex, black, shining : 

 head and mouth black, the former rather convex, with two large rufous spots 

 on the crown : thorax smooth, with a deep arcuate impression on each side, 

 within the hinder angles : elytra oblong-ovate, glossy black, very smooth, a 

 little beyond the middle, near the outer margin, a large round transparent white 

 spot, and rather within the apex a smaller one of the same colour : on the disc 

 of each are three rows of impressed dots, placed rather irregularly towards the 

 apex : body deep glossy black beneath : legs also black, with the four anterior 

 tarsi rufo-piceous : antennae rufo-ferruginous. 



This differs from Co. guttatus by the superior convexity of its body, and more 

 attenuated form, exclusively of the difference in the colour of its legs, &c. 



Five specimens of the above-described insect are in the collection 

 at the British Museum ; they were taken by Dr. Leach in Devon- 

 shire in the spring of 1825: — they are apparently new ; yet as 

 nearly half the species of Colymbetes in the above collection are 

 unnamed, and the species themselves are promiscuously arranged, 

 it is a difficult matter to decide upon their identity or disparity ; it 

 is therefore with considerable hesitation that I venture to pronounce 

 this, as well as other insects which I have described from the 

 Museum specimens, under such disadvantageous circumstances, as 

 novel. 



Genus LXXXV. — Agabus, Leach. 



Palpi, external maxillary with the second and third joints equal, the fourth 

 longer and subulated: lab rum bilobate: mandibles emarginate at the apex: 

 mentum trilobate, the central lobe small. Antenna? (of the males) with the 

 seven basal joints obconic, the three following compressed, internally dilated, 

 and serrated, the terminal small acuminate : head subovate : thorax elongate- 

 transverse : scutellum distinct : elytra ovate, attenuated : legs natatorial : an- 



g2 



