392 BULLETIN UNITED STATES GEOLOGICAL SURVEY. [rol.YI. 



the same size as in Gairibarus ; the flagellum is of the same size, extend- 

 ing to the terminal fourth of the abdomen, i. e., quite to the base of the 

 penultimate abdominal segment. Length of flagellum in the large 

 example, 44™™. 



The scale (exopodite) of the second antennse (Fig. 1) is quite similar in 

 form to that of Camharus ohesus var. latimanus and C. bartonii, but rather 

 narrower, the terminal spine being long and slender, acute; the thin edge, 

 blade, or expansion being narrow, and with the edge gradually narrow- 

 ing towards the spine, much more so than in C. ohesus or bartonii. The 

 scale has several impressed lines as seen in the living individuals of 

 Astacus and Camharus. The upper edge of the scale has a row of pits, 

 corresponding to the little tubercles for the insertion of the spinules in 

 the living species. The length of the scale is 7™™, and the breadth 2™™. 



The end of the third joint of the first antennal scape in the smaller 

 specimen reaches to near the end of the last joint of the second antennal 

 scape, though these parts are somewhat misplaced ; still in this respect 

 the species is more like those of Camharus than of Astacus, in which 

 {A. fluviatilis, from Europe) I observe that the joints of the scape are 

 very much shorter than in Camharus, and that the end of the scape does 

 not reach beyond the end of the ijenultimate joint of the second antennal 

 scape. 



Rostrum. — The shape of the rostrum can fortunately in the smaller 

 example be made out tolerably well. Its gen eral shape is much as in 

 Camharus affinis, but it is a little narrower, the frontal si^ine being 

 unusually long and narrow. The two lateral spines are present and are 

 situated about one-half way between the base of the rostrum and its 

 long slender acute tip. This relation is unusual, as in C. affinis, the tip 

 is much shorter and the lateral spines are situated near the tip. The 

 edges of the rostrum are raised; the lateral spines at the base, so well; 

 developed in the living species, are in these fossils obscurely marked on 

 one side, owing probably to the distortion of the carapace. Length of 

 rostrum, 7™™ ; breadth, 3™". 



Carapace. — The transverse curved line of the carapace (cervical groove 

 of Huxley) is as usual in living Camhari, and there are indications of 

 the lateral spines. The surface is irregularly and finely pitted as in most 

 Camhari. Length (in the smallest and best preserved specimen) of 

 carapace, 18™™; breadth of posterior edge, 12™™. 



The mouth-parts are not indicated, and the branchice cinnot be de- 

 tected so as to ascertain how many pairs there are, and whether the 

 species belongs to Astacus or Camharus. 



The first, largest pair of legs, are rather shorter and stouter than in 

 living Camhari, the chela is moderately broad, and of much the same 

 proportions as in C. affinis, but the pincers (propodite and dactylopodite) 

 are rather shorter and stouter, and the surface of the chela and of the 

 whole limb is much more coarsely tuberculate, being in this respect 

 somewhat as in Astacus flumatilis of Europe. The third joint from the 



