1913.] NATURAL SCIENCES OF PHILADELPHIA. 631 



slightly thickened, the extremities joined by a trigonal, dentiform 

 callus and with an obtuse tooth near the upper extremity. Alt. 1.5, 

 greatest diameter 3.5, least diam. 3 mm. 



About twenty specimens of this striking species were taken just 

 below the surface of the ground, between the buttresses of an old 

 stump at Camp 39, M. & M. R. R. The species is named for Mr. 

 A. B. Jekyll, of the firm of contractors, who made our trip to the 

 Madeira and Mamore Rivers possible and who extended to us so 

 many personal courtesies. It differs from E. reyrei Souverbie by 

 its smaller size, the absence of a swelling behind the lip and by the 

 tooth on the outer lip. 



Genus SYSTROPHIA Pfr. 

 SystropMa eatoni n. sp. PL XXII, figs. 14, 15. 



Shell widely, perspectively umbilicate, rather thin, diaphanous, 

 shining, grayish or grayish-yellow, the yellowish tint apparently 

 depending on an extremely thin, fugaceous epidermis; spire sub- 

 immersed, embryo nearly smooth, and, beginning on the second 

 whorl, everywhere sculptured with irregularly sized and spaced 

 costulse, retractive on the early whorls, but arcuate on the last whorl, 

 and becoming protractive as they cross the base and dip into the 

 umbilicus; obsolete spiral markings present on the last whorl and 

 perceptible with a strong glass on the early whorls; sutures deep 

 and well defined; periphery evenly rounded except on the last 

 eighth turn, where an oblique flattening of the upper portion produces 

 a subangulation. Whorls 10, slightly convex above, more rounded 

 below, very narrow, the last more than treble the width of the 

 penultimate; not descending in front. Aperture obliquely sub- 

 triangular; lip white, thickened but not expanded, depressed above, 

 extremities distant; callus uniting the extremities thin, but well 

 defined externally; no internal teeth. 



Alt. 5.75, greatest diam. 14.5, least diam. 12.5 mm. 

 This species is closely related to ^S. stenogyra Pfr., but it differs by 

 being smaller, with scarcely so many whorls and a narrower aperture, 

 and by the lip being thickened but not expanded. S. helicycloides 

 Orb. is more depressed, with a distinct impression extending over 

 the last third of the last whorl. A single, half grown specimen was 

 taken at Abuna, Bolivia, six living specimens at Camp 35, M. & M. 

 R. R., and seven living specimens were sent from some point not 

 noted on the same railroad by Mr. C. W. Eaton, of the engineering 

 force, for whom I have named the species. 



