2 Mr. C. C. Babington's Descriptions 



genus in the proportions of the joints of its palpi and antennae, 

 the structure of its mandibles, and the singularly pitted elytra of 

 the female. In the first group of the genus Colymbeles (^Rantus, 

 Eschsch.), we have a series of species closely allied to our C. no- 

 tatus and agil'is, but most of them at once distinguished from all 

 the English species by the form of the apex of their elytra. In 

 our native insects of this group, that part is uniformly rounded 

 and obtuse, but in the South American specimens contained in 

 this collection each elytron is obliquely truncate in such a manner 

 as to form a sharp point at the suture (PI. 1, fig. 2 6). The sin- 

 gular structure of the anterior claws of the males is worthy of 

 notice, one of them being much longer than the other, broad, flat- 

 tened, and fixed at a right angle with the last joint of the tarsi; 

 the other slender and setaceous, and about a third part shorter 

 (PI. 1, fig. 2 a). This structure occurs in the claws of C. notatus, 

 but in no other English species which I have had an opportunity 

 of examining. In C. angusticoUis will be found a form of thorax 

 which has never before fallen under my notice in this genus. The 

 species of Hydroporus will be observed to resemble closely some 

 of those contained in our English cabinets, but yet to be clearly 

 distinguishable from them. 



At the conclusion of the paper, I have characterised three new 

 generic forms of great interest ; and as the species upon which 

 they are founded are amongst the more minute of those contained 

 in this family, and are nearly the first small water insects which 

 have been brought from the tropics, I cannot but consider them 

 as a proof of the very rich harvest which awaits the active and in- 

 dustrious collector, who may be induced to turn his attention to 

 the minuter insects of those countries. The first, which I have 

 denominated Hydrojwromorp/ia, has the general appearance of an 

 Hydroporus, closely resembling H. oblongus, Power (Steph. 111. 

 (M.) 5, p. 4.'37), but it has a conspicuous scutellum ; the structure 

 of its labial palpi is quite different, having the three first joints 

 very short, and the first joint of its internal maxillary palpi is 

 longer than the second, not very short as in Hydroporiis. The 

 second new generic form (^Anodoclicilus, Bab.) also closely resem- 

 bles a minute Hydroporus, from which it differs by the three basal 

 joints of its external maxillary and labial palpi being transverse, 

 and the terminal one emarginate, the first joint of the internal 

 maxillary long and slender, and the second subulate, and by the 

 want of the least trace of a tooth in the centre of the mentum. 

 The third new genus (Desmopachria, Bab.) has the outward ap- 

 pearance of a minute Hygrotus, but is distinguished from that 



