548 RESULTS OF THE LABORS 
_ My successor, General Robert B. Campbell, took 
the field in May, 1853 ; and under his orders, the sur- 
vey of the Rio Grande from Loredo to its mouth, anda 
portion in the cafion of that river, was completed be- 
fore the close of the year. 
In the department of Zoology, much has been 
accomplished by officers of the Commission. The col- 
lectors were Mr. J. H. Clark, Dr. Thomas H. Webb, 
and Mr. Arthur Schott. 
A large collection of fishes was made in the waters 
of the Rio Grande, and in the tributaries of the Gila 
and the streams to the south of it, by Mr. Clark, a 
large portion of which have proved new to science. 
Many of these have already received a sort of publicity 
through the proceedings of the Academy of Natural 
Sciences. Among them are some new genera. Repre- 
sentatives of the families Zabridae and Characini, were 
detected,in the waters of the Rio Grande. , 
_ A considerable number of reptiles were collected 
by Messrs. Clark and Schott, embracing new genera 
and species, which have already been described by 
Professors §. F. Baird and Charles Girard, in the 
Proceedings of the Academy, and their ‘“‘ Catalogue of 
North American Serpents,” published by the Smithso- 
nian Institution. In speaking of the collection sent 
home by Mr. Clark in the spring of 1852, these dis- 
tinguished naturalists remark, that ‘It will be perfect- 
ly safe to say, that one hundred undescribed species of 
North American vertebrate animals have been added 
_to our fauna. The entire annals of zoological history 
scarcely present a parallel to this case.” 
Dr. Webb made an interesting collection of fishes, 
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