256 Annals of the Carnegie Museum. 



Genus ScHMiDTELLA Ulrich. 

 4. Schmidtella crassimarginata Ulrich. 



Schtnidlclla crasshnarginala Ulrich, 1890. American Geologist, Vol. X, p. 269, 

 PI. LX, figs. 27-30. 



Several right valves which appear to belong to this species have 

 been found in the Chazy. They also resemble Schmidtella crassi- 

 marginata ventrilabiata Ruedemann in general form, but lack the 

 lip-shaped projection on the ventral border. They 

 are longer than either Ulrich's or Ruedemann's 

 specimens, the length being 2.5 mm. and the height 

 1.5 mm. 

 ^'^- ^ ■? • Description. 



Schmidtella cras- 

 simarginata Ul- Carapace small, strongly conve.x, with a depressed 



rich. Photograph border, which is widest at the middle of the valve. 



of a specimen The hinge-line is straight, and nearly equals the 



from Valcour Is- length of the shell. The greatest convexity is at 



about the middle of the valve. The slope to the 



dorsal margin is flattened, while the other slopes are convex. The 



border is wide, smooth, and slopes away from the main body of the 



shell, from which it is separated by a narrow, sharp groove. The 



surface of the shell shows a few large scattered depressions. 



Locality. — This shell is commonest in the "trilobite layers" at 



Sloop Bay, Valcour Island, New York. 



Explanation of Plates. 



Plate XXXIII. 



1. Glossina belli (Billings). A pedicle valve from the base of the Upper Chazy. 

 Valcour Island. X 2. Carnegie Museum. 



2. Lingula brainerdi Raymond. A partially exfoliated valve from the sand- 

 stone at the base of the Chazy on Valcour Island. X 2. Carnegie Museum, 



3. 4. Lingula columba Raymond. Two valves from the base of the Upper 

 Chazy at Valcour Island. X 2. 3 is in the Yale University Museum, and 4 in 

 Professor Hudson's collection. 



5, 6. Lingula lyelli Billings. Valves representing the two forms referred to 

 this species. The specimens are from the sandstone of the Aylmer formation at 

 Allumette Island, Quebec, and are in the Museum of the Geological Survey of 

 Canada. 



7-17. Dorsal and ventral views of a number of specimens of Camarotoechia 

 plena Hall, to show variation in outline and in the number and strength of the 

 plications. All natural size, and the specimens are in the Carnegie Museum. 

 All are from the same layer at Cystid Point, Valcour Island. 



