308 GEOLOGICAL SURVEY OF THE TERRITOEIES. 



collected by Dr. Yarrow, Lieutenant Wheeler's Survey west of the 100th 

 Meridian. 



Zimapan, Mexico, (Prof. W. Dunker coll.), Clans. 

 This species is exposed to considerable variation, so that I was mis- 

 led by the rather indifferent figure of Baird in considering it as dis- 

 tinct from E. caldivelli from Lake Winnepeg ; and described it as E. 

 clarJcii. The specimens from New Mexico are large and well developed, 



little and a larger than in the majority of the 

 Kansas specimens. They agree well with 

 Claus's figure of the shell, and the appendages 

 are much as he figures them, so that as the 

 species is abundant in i?ew Mexico, I do not 

 doubt but that it extends to Zimapan, Mexico, 

 and thus the name for our most common and 

 widely spread Estheria should be mexicana of 

 Fis. lo.-Estheria mexicana, en- Claus. This spccics is allied to the European 

 larged four times. E. dahcilacensis, but the beak is fuller. 



I have ventured to place E. dmikeri from Zimapan, Mexico, as a syno- 

 nym of this species. Baird's description is almost identical with that of 

 his E. caldivelli; but my ISTew Mexican specimens have the same out- 

 line, the same number of lines of growth, and only differ in having less 

 full and i^rominent beaks ; but the artist may have exaggerated this 

 feature in his drawing, though it is referred to in Baird's description, 

 yet some smaller Kansas specimens have fuller beaks than the New 

 Mexican ones, but, as the locality (Zimapan) and collector (Dunker) 

 are the same as Claus's E. mexicana, there is little doubt but that taking 

 into account the tendency to variation in this species our synonymy is 

 correct. 



EsTHEKiA MOESEi Packard. 



Plate XXIV, fig. 7 ; XXVI, figs. 1, 2. 



Estlieria morsei Packard, Amer. Journ. Sc, II, Aug. 1871. 



Sixth Report Peab. Acad. Sc. Sa]em, 56, June, 1874. 

 Hayden's U. S. Geol. Surv. Terr, for 1873, 619, 1874. 

 Morse's First Book of Zoology, 149, fig. 138, D. (No name.) 



Shell much fuller, more globose than in any of the preceding species, 

 with fuller, more prominent, less oblique, and centrally situated beaks; 

 shell oblong oval, of a i^ale horn or amber color. Dorsal edge shorter 

 than in E. mexicana^ and in front of the beaks, instead of being straight 

 and suddenly curved downward, is regularly rountler, much as in E. 

 helfragei ; posteriorly the dorsal edge slopes rapidly downward, without 

 the well marked angle of E. mexicana. Coarse punctures between the 

 lines of growth, rather coarser than in E. mexicana, there being on an 

 average 5-10 of these marking between the ribs in the center of the 

 valve. Plate XXIV, fig. 7, also represents the markings at the edge of 

 the s'lell. 



Second antennge, with a larger scape than in E. helfragei, 17 joints in 

 the up{)er, 16 in the lower, fiagellum. Legs of the male with a smaller 

 lower division of the fiagellum, and a smaller gill than in E. bel/ragei, 

 while the upper division or oviger is much shorter and broader than in 

 any of the foregoing species, being no longer than the gill. The hand 

 is apparently a little thicker than in E. belj'ragei. 



Telson much as in E. mexicana, with about 20 pairs of teeth, coarser 

 than in E. helfragei, about 5 pairs of which are much larger than the 

 others. 



Length, 12.2"''"; height, 8.2"'"; thickness, G""™. 



