58 J. 31. Cla/rke — Clymenia in Western Neio York. 



The material obtained is from a calcareous concretion found 

 in Shurtleff's Gully in Livingston County, N. Y., not far up 

 in the shales of the Naples beds. This concretion has also 

 afforded specimens of an undescribed Gephyroceras of very 

 common occurrence in this fauna, Tornoceras uniangulare 

 Conrad, Bactrites sp. nov., or very like B. carinatus Miins- 

 ter, Loxonema Noe Clarke, Palceotrochus prcecursor Clarke, 

 Platy stoma minutissimmn Clarke, Bellerophon, sp. indes., 

 Styliolina fissuretla Hall, Cardiola [?] Doris Hall, Lunuli- 

 cardium, sp. nov., common throughout the fauna. 



The specimens consist of about thirty examples of a single 

 species in an exceptionally fine condition of preservation, 

 affording the various stages of growth from the protoconch to 

 maturity. As the exterior of the shell is so exquisitely 

 retained and the earlier whorls are compactly filled with silica 

 it has been a difficult task to determine with precision the 

 variations in the form of the suture. 



Description of the species. — The mature individuals are of 

 small size, the largest example retaining the chamber of habi- 

 tation having a diameter of 14 mm . The outer chamber is long, 

 extending nearly three-fourths the length of the last volution. 

 The shell is widely umbilicate, the successive whorls scarcely 

 overlapping ; the number of revolutions from the proximal 

 end of the protoconch is h\ or 6. The chamber of habitation 

 is subtrapezoidal in section, widening at the base where its 

 sides are rather abruptly incurved to embrace the ventral sur- 

 face of the inner whorl. The sides slope outward with some 

 convexity and the ventrum is flattened, sometimes very slightly 

 convex or concave. 



The protoconch is broad, transversely ellipsoidal, and has a 

 diameter of 9 mm . In adolescent growth stages it is not prom- 

 inent on account of the absence of any contraction of the 

 tube at the beginning of the first chamber. In the Groniati- 

 tinag this contraction is an important character especially well- 

 developed m the genera of the Primordiales. The early 

 whorls are broad and very shallow in section, and in them 

 the flattened ventrum of the body whorl is not apparent. 

 For the first four revolutions of the tube, the union of 

 the successive whorls is essentially an apposition, the slight 

 overlapping at maturity indicating a tendency to diminution 

 of umbilication as a geratologous character. The 2d, 3d, 4th 

 and 5th whorls are very broad on the periphery, their vertical 

 to ventral diameter being as 1 to 3*2, 1 to 3, 1 to 2 - 5, 1 to 2, 

 respectively. In the 4th whorl the ventral surface becomes 

 rapidly convex by the filling out of the ventro lateral slopes, 

 and with the 5th and 6th whorls the increasing lateral appres- 

 sion brings into prominence the narrow flattening of the ven- 



