394 BULLETIN UNITED STATES GEOLOGICAL SURVEY. [VolYI. 



were collected by Mr. Clarence King, in charge of the Survey of the 

 Fortieth Parallel. The three species are Astaeus suhgrundialis, from a 

 fresh water deposit in the territory of Idaho, near Hot Spring Mountain, 

 Astaeus clienoderma, and A. hreviforcejps from Catharine's Creek, Idaho. 



They are quite imperfect and are stained nearly black with iron, 

 and present a very different appearance from the fossils of the Lower 

 Tertiary (Eocene?) beds from which Camharus primcevus were obtained. 

 The beds containing the Idaho specimens, according to Cope, were asso- 

 ciated with fossil cyprinoid fishes (Proc. Amer. Phil. Soc, xi, p. 538), 

 which were deposited in a fresh water basin, once a lake, which has, at 

 a comparatively late period of geological time, been elevated and desic- 

 cated. Of the six genera of fishes described from these deposits " one of 

 them, Semotilus, is recent, while three are closely allied to existing gen- 

 era, viz, Ehabdofario, Anchybopsis, and Oligobelus. Distichus and 

 Mylocyprinus are less nearly related to living genera." 



"The molluscs of this formation have already been described by F. B. 

 Meek, and they, like the fishes, determine it to be lacustrine and fresh, as 

 already stated by Professor Newberry. The species are stated by Meek 

 (Proc. Acad. ISTat. Sc. Phil., 1870, 56) to be distinct specifically, and in 

 some cases generically, from all others hitherto described from the West. 

 Leidy observes (Proc. Acad. Nat. Sc. 1870, 67), that mammalian remains 

 received from Captain King's expedition include portions of Mastodon 

 mirificus and Hqmis excelsus, which indicate an age similar to that of 

 the Bad Lands of the Niobrara, which Hayden calls Pliocene. The re- 

 mains [of fishes] described in this paper furnish few means of determin- 

 ing the age of the deposit. There is, however, a great probability of 

 their being later than Miocene, and nothing to conflict with their determi- 

 nation as of Pliocene age." 



The fossil remains of two of the three species (I have not seen those of 

 Astacics suhgrundialis Cope) show that they had attained as great a size 

 as the larger individuals of our existing species, and must have lived 

 under the most favorable conditions and in fresh water. 



It is impossible from the remains to ascertain whether they belong to 

 the genus Astaeus or Cambarus, as these specimens are very imperfect. 

 A. ehenoderma in the carapace and chela seems to approximate in size 

 and form to Astaeus fluviatilis of Europe, and it is not improbable that it 

 is an Astaeus rather than a Cambarus. That this is the case is rendered 

 probable by the form of the tubercles at the base of the rostrum ; but in 

 the form of the carapace and the absence of the group of spines low 

 down on the side of the carapace, which are also wanting in Astaeus flu- 

 viatilis but present in Cambarus affinis (though absent in C. bartonii) the 

 fossil forms are allied- jjerhaps rather to Cambarus, but as these characters 

 are inconstant in Cambarus, they may not prove much as to the generic 

 affinities of the fossils. On the other hand, the rostrum is large, more 

 triangularly ovate in the Idaho fossils, and the scale of the larger an- 



