LYMN^EHLE OF NORTH AMERICA. 237 



SHELL : Small, rather solid, varying from ovate to elongate-ovate ; 

 color light yellowish or brownish ; surface shining, with heavy growth 

 lines crossed by very fine, almost microscopic spiral impressed lines ; 

 nuclear whorls as in cubensis;. whorls 5-5 J^, well rounded, the spire 

 whorls inclining to become shouldered, the body whorl very convex; 

 spire attenuated, broadly conical, about as long as the aperture ; sutures 

 well impressed ; aperture ovate or roundly ovate, its axis nearly parallel 

 with that of the shell ; outer lip thin, with an internal varix edged with 

 violet; inner lip reflected and turned back over the umbilical region, 

 forming a narrow, somewhat elevated expansion; parietal wall with 

 marked callus; umbilical chink large and conspicuous; axis of the 

 whorls as in cubensis. 



Length. 

 7.00 

 6.75 

 6.00 

 7.75 

 7.00 

 7.00 

 6.00 



TYPES: Umbilicata, Amherst College. Cotypes: Phil. Acad. 

 Sci. (eight specimens, No. 58507) ; Smithsonian Institution, No. 28158 

 (Binney's No. 8249); Museum of Middlebury College, Vermont; 

 griffithiana, Smithsonian Institution, two specimens, No. 119467. 



TYPE LOCALITY: New Bedford, Massachusetts, for umbilicata; 

 Charlotte Lake, Columbia County, New York, for griffithiana. 



ANIMAL : Not differing from the other small Lymhseas. 



JAW (plate VI, fig H) : Wide and low, much arched with a 

 narrow, acute median projection on the ventral margin. 



RADULA (plate VIII, figs. A, B) : Formula : *LVff + J+i+t+f+s 1 - 6 ? 

 (22-1-22) ; central tooth with rather wide cusp; lateral teeth tricuspid, 

 the mesecone very long and wide, the entocone and ectocone smaller; 

 the fourth and fifth laterals become elongated, the entocone moves 

 toward the distal end and becomes larger and the mesocone becomes 

 smaller; the true marginals begin at the seventh tooth and consist of 

 a long and narrow, bifid entocone, a larger mesocone and a smaller 

 ectocone ; one or two very small serrations appear on the reflection 

 above the ectocone; the outer marginals become claw-like with from 

 three to five serrations at the distal end and several smaller serrations 

 on the outer margin. There are about 90 rows of teeth. The teeth 

 are quite uniform, little variation being seen in several membranes 

 examined. In one membrane the seventh tooth (transition) was dis- 



