Mr. Babington on a new British Species of Colymbetcs. 53 



In examining critically the genera of Neottidea, I have been 

 surprised to find that this Decaisnia is identical with Pres- 

 cottia ; a circumstance easily overlooked, since the species is 

 somewhat different in habit from any of the Prescottias 

 hitherto published, and is moreover so represented in the 

 figure that accompanies M. Brongniart's memoirs as not to 

 call to mind the peculiar cucullate fleshy lip and revolute floral 

 envelopes of Prescottia. I find, however, that both these cha- 

 racters really exist in Decaisnia, 



M. Brongniart relies upon the adhesion of the lateral sepals 

 and labellum into a pouch, two pollen masses, and a pair of auri- 

 cles to the anther-bed, as characteristic features of Decaisnia ; 

 but the first is equally the attribute of all Prescottias, and the 

 others are of little moment. I am not able to ascertain whe- 

 ther the granular pollen masses are simple or two-lobed, 

 although I possess an excellent specimen of D. densiflora, 

 through the liberality of M. Ad. Brongniart, so very difficult 

 is the examination of the minute fructification of these plants : 

 but even if the pollen be as is represented in the figure in 

 Duperrey's Voyage, it would not constitute, per se, a generic 

 difference from Prescottia ; and with regard to the auricles of 

 the anther-bed, they occur in P. plantaginea itself, and in P. 

 stachyodes form a still more striking feature in that part. 



Although the name Decaisnia must therefore be abolished, 

 I do not think it desirable to restore it to those Indian Neot- 

 tidece, originally so called by me, and afterwards, at the re- 

 quest of M. Brongniart, altered to Cnemidia, for this would 

 be to increase the confusion of names. It will, I think, be 

 better that some new genus should be taken to commemorate 

 the distinguished merits of M. Decaisne. 



VIII. — On a new British Species o/'Colymbetes. By Charles 

 C. Babington, Esq., M.A., F.L.S., F.G.S., &c. 



The water Coleoptera of South Britain have now been so 

 carefully studied, that it is far from probable that any new spe- 

 cies should yet remain to be discovered amongst the larger 

 forms ; it is therefore with the greater satisfaction that I now 

 introduce to the entomological readers of the Annals of Na- 

 tural History a new species of Colymbetes, discovered by the 

 Rev. J. L. Brown in Horning marshes, Norfolk, in the month 

 of March, 1839, and again found in the same place in March 

 1 840. This insect appears referable to the section Agabus of 

 Erichson, in which the labial palpi have the third joint a very 

 little shorter than the second, the claws being equal and 



