304 



GEOLOGICAL SURVEY OF THE TEEEITORIES. 



Synopsis of the species. 



Shell large, flat; beaks close to anterior end- and very small ; second an- 

 tennae 13- and 15-jointed E. californica. 



Like californica, but with more prominent beaks, dorsal edge sloping 

 directly down to the posterior end E. newcomhii 



Shell loug and narrow; beaks small, situated very near anterior end; 

 telsou armed with small fine teeth ; bauds of male short and thick ; 

 flagella 15- and 14-joiuted E. compleximanus 



Shell more swollen ; beaks larger, and farther from anterior end ; dor- 

 sal edge short, suddenly sloping to posterior end ; flagella 17- and 

 IC-jointed; telson with larger teeth interpolated in the smaller 

 ones E. mexicana 



Shell still more globose than in E. mexicana; beaks more prominent m 

 anterior third of shell ; flagella 17- and 16-jointed E. morsei 



Shell globose ; beaks large and prominent, more central than in pre- 

 ceding species ; flagella 14- and 15-jointed E. helfragei 



Shell very large, thick, globose, swollen ; beaks larger and fuller, cen- 

 tral ; with more numerous lines of growth than any preceding spe- 

 cies; flagella 17- and 16-jointed E.jonesii 



EsTHERiA CALIFORNICA Packard. 



Plate IV, figs. 1-5. 



Esthej'ia californica Packard, Sixth Rep. Peab. Acad. Sc, Salem, 55, 1874. Hayden's 

 U. S. Geol. Surv. Terr, for 187i5, 618, 1874. Lenz, Estheria californica, &c., 

 Liibeck, Aug. 5, 1876. 



Shell remarkably thin, so that at first sight it might be mistaken for a 

 Limnadia; in outline subtriangular ; the umbones unusually small, 

 very oblique, flattened, and situated much nearer than usual to the 



anterior edge ; dor- 

 sal edge convex, curv- 

 ing gradually to the 

 rounded x>osterior 

 end. Eighteen to 

 thirty-five lines of 

 growth. Shell very 

 smooth, shining, with 

 very fine granulations 

 too numerous to be 

 counted with a two- 

 thirds-of-an-inch trip, 

 let; when more highly 

 magnified they ap- 

 pear as in Plate 

 XXIY, fig. 5. First 



Fig. 7.— Estheria californica. auteunai rathCT SlcU- 



der, the papillae, however, not very well markec^, Second antennae with 

 the upper flagellumlS-jointed, and much shorter than the lower, which is 

 15-jointed. Twenty-two pairs of feet. The gill is rather small and short ; 

 the upper division of the flabellum very long and slender, reaching to 

 the back of the animal; the lower one acutely triaiiglar; the sixth en- 

 dite is a little longer than the lower flabellum, and is broader in the third 

 than in the first pair of limbs; the fifth endites are slender, long, and 

 narrow, finger-shaped. The telson is armed above with numerous fine 



