Rev. H. Clark on the Mexican Species of Hydropori. 173 



XVIII. — On the Mexican Species of Hydropori. 

 By the Rev. Hamlet Clark, M.A., F.L.S. 



A very interesting and valuable collection of Coleoptera, made 

 by M. Truqui during his residence of several years in Mexico, 

 has recently passed into the hands of my friend Mr. Alexander 

 Fry. The Dytiscidae of this collection I have, by Mr. Fry's 

 kindness, carefully examined. Some of the species of the group 

 are well known; but many others (and these especially the 

 smaller species) appear to be new to science. The genus Hydro- 

 porus especially (represented by sixteen species) presents no 

 form that I am able to recognize as already described by Say, 

 Melsheimer, or Leconte. Say's descriptions are somewhat im- 

 perfect, and, in the absence of typical specimens, often insuffi- 

 cient ; and I have been unable to examine the fifth volume of 

 the ' Annals of the Lyceum of Natural History of New York/ 

 in which many of Leconte's species are described. With the 

 aid, however, of the admirable analysis of the Hydropori of the 

 States, drawn up by Dr. Leconte, and published in the f Pro- 

 ceedings of the Academy of Natural Sciences/ April 1855, and 

 especially (in some cases) of type-specimens of interesting spe- 

 cies described by him, which that gentleman has added to my 

 cabinet, I have been able to satisfy myself of this, at least, that, 

 whatever may be the' characterized species of Mexican Hydro- 

 pori, none of them are to be found among the species which I 

 have been recently examining. I propose therefore in this paper 

 briefly to describe the new species from Mr. Fry's cabinet and 

 my own, having first enumerated those Mexican species of this 

 genus that (so far as I know) are already determined. With the 

 aid of Dr. Leconte (by his interesting set of types from his cabi- 

 net, and also copies of valuable papers by him on North-American 

 Coleoptera), and by the kindness of M. Bonvouloir of Paris (who 

 has entrusted to me for comparison type-specimens of North- 

 American species named by M. Aube), I believe that the list is 

 tolerably accurate. The prefix to each species of a letter and 

 figure indicates the subsection of the genus, as adopted in the 

 following paper, to which the species may be referred. 



Species already described by authors : — 

 (A. 1.) H. punctatus, Say, Long's Second Exped. Philad. 1824, 

 ii. 271. 



, Aube, Species General, 1838, 471. 



(A. 1.) H. cuspidatus, Germ. Faun. Ins. Eur. v. t. 4. 



Hyphydrus notatus, Say (?). 

 (B. 2.) H. lacustris, Melsh. ;" Say, Trans. Amer. Philos. Soc. 

 1823, ii. 103. 



H. pulicarius, Aube, Species General, 1838, 495. 



