New British Colymbetes. xxv 



the tips of the palpi and the apices of the joints of the antennae, those towards the 

 base excepted, narrowly dusky. Thorax short, transverse, very considerably narrowed 

 anteriorly, posteriorly not much narrower than the base of the elytra ; widely emargi- 

 nate in front, the anterior angles reaching up to the eyes and closely embracing the 

 head, acute ; the sides oblique and rounded, distinctly margined ; the base sinuated ; 

 above convex, with a small fovea on the disk, a row of punctures at the apex and ano- 

 ther at the base, the former somewhat deep and irregular, the latter smaller, inter- 

 rupted in the middle, crowded in a slight depression on each side towards the posterior 

 angles, and continued on the lateral margins, where they become scattered ; the sides 

 broadly ferruginous. Scutellum black, glossy, very finely strigose. Elytra ovate, 

 rather broad, the sides somewhat arcuate or rounded, gradually increasing in width to 

 a little behind the middle, when they are rather abruptly and very considerably at- 

 tenuated ; the apex obtuse, slightly rounded ; very convex, especially towards the 

 base, and gradually sloping from the middle to the apex ; more distinctly punctate 

 towards the base ; glossy, nigro-fusco-subaeneous ; the shoulders, the outer margins of 

 the base and the lateral margins broadly testaceous ; the apex concolorous ; a short 

 row of fine, not very numerous punctures on each side of the suture posteriorly, and 

 four rows of more distinct impressions on each elytron, of which the innermost is the 

 most regular, the others being much scattered, especially after the middle and towards 

 the apex. Body beneath black ; abdomen attenuated, with the elytra projecting over 

 it, the posterior edges of the segments and the apex rufo-testaceous. Legs rufo-fer- 

 ruginous ; the femora, more frequently only the posterior, slightly clouded with fus- 

 cous ; anterior and intermediate tarsi with the three first joints in each considerably 

 dilated ; posterior tarsi with the four basal joints beneath furnished with very long 

 ciliae, which are often abraded. 



Female. — Obscure above, especially on the elytra, which resemble those of C. 

 Sturmii ; slightly broader behind, and shorter than the male ; head, thorax and scu- 

 tellum, shining; elytra very finely, closely and uniformly reticulate-strigose, much 

 better marked than in the males, the puncturing more obsolete and the sides more 

 fuscescent ; posterior and intermediate tarsi compressed, simple, not dilated ; posterior 

 tarsi without long ciliae. 



Closely allied to C. uliginosus, from which the form, sculpture, and the obscure 

 tint of the female, will readily distinguish it. It appears to have a still greater 

 affinity with A. Keichei of Aube (Iconog. et Hist. Nat. des Coleop. d'Europe, torn. v. 

 138, pi. 16, fig. 6), but as he does not mention the dissimilarity of the sexes, and as 

 his character represents the sculpture as " strigoso-subpunctatus," which does not 

 agree with our insect, it being distinctly reticulate-strigose, I lean to the conclusion 

 that it is a species not before described. 



Found in pools and ditches at Boldon Flats, county of Durham, in May and 

 June. 



I have possessed a female of this species for some years ; and although unable to 

 assign it to any recorded British species, I was yet unwilling to describe it, until I 

 could do so from ampler materials, which this season has placed at my disposal ; 

 about twenty specimens having occurred, forming a series which exhibits little vari- 

 ation. 



I have pleasure in acknowledging my obligations to my friends Messrs. Samuel 

 Stevens and E. W. Janson, for their kindness in forwarding me specimens of rare 

 VII. APPENDIX. DD 



