Palceozoic Bioalved Entomostraca, 343 



Leperditia alta et L. Jonesi, Hall, Palaeoutol. New York, vol. iii. 1859, 



pt. 1, pp. 372, 373. 

 Leperditia alta, Meek, Report Geol. Surv. Ohio, vol. i. pt. 2, Paldeon- 



tology, 1873, p. 187, pi. xvii. figs. 2, a, b. 

 Leperditia alta, Jones, Ann. & Mag. Nat. Hist. 1881, ser. 5, vol. viii. 



p. 346. 

 Leperditia alta, Whitfield, Report Geol. Wisconsin, vol. iv. 1882, p. 323, 



pi. XXV. figs. 8, 9, and vol. i. 1883, p. 198, fig. e. 



At page 346 of the Ann. & Mag. Nat. Hist, for November 

 1881, noting L. alta, and referring to the usual association of 

 relatively large and small valves (in Ohio, New- York State, 

 Canada, and the Arctic regions), I mentioned that Dr. James 

 Hall (recognizing his figs. 2 h and 2 c as both right valves) 

 has proposed to distinguish the larger form as L. Jonesi. 

 The first name would seem to be more applicable to the larger 

 (fig. 2 c) than to the smaller form (fig. 2 h) ; but probably 

 Dr. Hall has good reason for his decision. In this case my 

 figs. 6 a, 6 Z>, pi. 7, February 1856, are probably L. Jonesi, 

 Hall ; and so may Meek's fig. 2 a of a specimen from the 

 Helderberg group, Greenfield, Ohio. A specimen of " L. 

 Jonesi " (from the Waterlime of the Lower Helderberg) in 

 the American Museum of Natural History at New York, I 

 have observed to have not only a reticulate muscle-spot, but 

 also to be somewhat gibberous on the postero-dorsal margin 

 of the left valve. This feature is shown to a slight extent on 

 the small left valve (fig. 7 a, pi. 7, February 1856), and may 

 well exist in the left valve of the larger form, as it is not un- 

 common on the left (smaller) valve of several Leperditia^, 

 such as L.fonticola, Hall, from Wisconsin*, and L. britannica, 

 Rouault, from Brittany and Normandy. In L.faba, Hall, from 

 Indiana, the dorsal swelling on the left valve appears to be 

 on the anterior and not on the hinder portion f. 



In the McGill University Museum. Labelled " 573.'" 

 ^^ Leperditia alta " (Conrad), Am. Mus. Nat. Hist. Lower 

 Helderberg Group, Tentaculite Limestone, Schoharie, N. Y. 



In a very dark grey limestone full of Tentaculites &c. are 

 some imperfect specimens. The best of them appears to 

 belong to the larger form {L. Jonesi) of the two usually 

 associated together in the Lower-Helderberg rocks. L. alta 

 occurs also in an equivalent formation in Pennsylvania. 



* Leperditia fonticola, Hall, Twentieth Ann. Rep. Regents Univ. 

 N. Y. &c. revised edit. 1870, p. 428, pi. xxi. figs. 1-3. " In limestone of 

 the Niagara riroiip, near Fond-du-Lac, Wisconsin." L. fonticola is said 

 to be abundant in the Niagara Group at Bvron, Wisconsin (' Rep. Geol. 

 Wisconsin,' vol. i. 1883, p. 187). 



t Twenty -seventh Ann. Rep. Reg. Univ. N. Y, &c. 1875-6, pi. xxxii. 

 figs. 1-3, with Bei/richin (granulosa., Hall, fig. 4, both from the Niagara 

 Group of Central Indiana. (No descriptive text.) 



