FOSSIL ASTACID^. 155 



No remains of Crustacea near the Astacidae have been found in tlie Wealden, which 

 is of fresh-water origin, while the Cretaceous has yielded tlie genera Hoploparia and 

 Enoploclytia, which closely resemble tlie recent Homaridte. Hoploparia is found also in 

 the London Clay (Eocene). 



Schliiter* has described, under the name Astaats politus, a Decapod from the Lower 

 Chalk of Westphalia, in which the telson is divided by a transverse suture, as in the 

 majority of the Potamobiina; ; but the single specimen obtained is too imperfect to admit 

 of being definitely placed, the fore part of the carapace, including the rostrum, as well as 

 the terminal portion of all the legs, being lost.f 



It is only in the fresh- water Tertiary deposits of the Western United States that fossils 

 have been discovered which can be referred reasonably to the family Astacidae. Packard J 

 has described and figured by the name of Camharus primcvvus two specimens from tiie 

 Lower Tertiary beds (Eocene ?) of the Eear Eiver Valley in AYestern Wyoming. Judging 

 from Packard's figures, I should think that these specimens belonged to Astacus rather 

 than to Cambarus. The shape of the antennal scale and the chelaj indicate this. I fail 

 to see the close resemblance pointed out by Packard between these specimens and Cam- 

 harus affinis. The rostrum, as shown in the figures, resembles that of A. Dauricus as 

 nearly as any living form. Witli reference to the conditions under which these crayfishes 

 lived. Dr. Packard says : "The soft, fine, fissile, clayey shales of the Bear Eiver Tertiaries 

 contain not only a good many herring-like fish, but also genuine skates. The presence 

 of land plants mingled with marine animals shows that the waters were fresh, but com- 

 municated with the sea ; the conditions M'ere apparently tliose of a deep estuary, into 

 which fresh-water streams ran, and in these rivers lived the crayfish. The deposits were 

 probably Eocene, if these divisions are to be retained for tlie Tertiary deposits of the 

 West, and may liave been laid down nearer the ocean tlian those of Green Eiver." 



In 1870 Cijpe§ described tliree e.xtinct species of Astacus from fresh-water Tertiary 

 deposits in the Territory of Idaiio. The specimens were obtained by Clarence King, on 

 the expedition sent out for the geological exploration of the fortictli parallel west of the 

 Mississippi Eiver. I have not been able to find the specimens in the Smithsonian Insti- 

 tution, where they belong. 



The first species described by Cope is named Astacus suhgrundialis. In this form 

 the rostrum is narrow, concave above, acute, with five spinous jjoints on each side and 

 a terminal recurved spinelet ; two post-orbital tubercles on each side, the anterior pair 

 spiniform ; surface of the carapace smooth or obsoletely wrinkled ; abdominal pleura promi- 

 nent and acuminate, those of the second segment four times as wide as the others ; chelse 

 nearly smooth, not granulate, the superior edge spiniferous ; the longitudinal groove of the 

 carpus is well marked, and this segment is not spiniferous ; the antennal scales are large, 

 and extend nearly to the tip of the rostrum ; areola of moderate width. Length to cervical 



* Neue Fische uutl Krebse aus dcr Kreide von Westphalen. Vou Dr. W. von dcr Marck und Dr. CI. 

 Schliiter. Palaeontograpliica, XV. 302, Taf. XLIV. figs. 4. 5, 1S68. 



f So also witli tlie genus Astacodcs founded by Bell (Mon. Foss. Malacostr. Crust. Great Britain, Pt. 

 II. Crust, of the Gault and Greensand, p. 30, PI. IX. figs. 1-6, 1862) for the reception of Mei/eria fiikifer 

 Phillips from the Speeton Clay. 



X "fossil CrawGsh from the Tertiaries of Wyoming," Amer. Nat., XIV. 222, 223, March, 1880. " On 

 a Crayfish from the Lower Tertiary Beds of Western Wyoming," Bull. U. S. Geolog. and Geograph. Surv. 

 Terr,, VI. 391-397, with two cuts, September, 18S1. 



\ "On Three Extinct Astaei from the Presh-water Tertiary of Idaho," Proc. Amer. Philosoph. Soc, 

 XL 605-607, 1870. 



