334 NORTH AMERICAN INDEX FOSSILS. 



the backward sweeping curve is the anterior, the most projecting 

 end, basally, being the posterior (see, further, Ulrich and Bassler, 

 ioc. cit., 1908, p. 280). 



Most living ostracods are marine or brackish water types; the 

 Cypridse, however, are an exception, occurring in fresh water. 

 They are gregarious, either Hving as plankton, or leading a ben- 

 thonic life in shallow ocean depths. Most of these shells are 

 minute and will usually be overlooked, unless searched for with 

 a lens on the surfaces of fine shale laminae. Washings of the 

 residue of weathered or dissolved rocks often yield a rich har- 

 vest of these organisms. 



Literature. 



A. Palcpozoic. 



1858. JonCvS, T. Rupert. On the Palaeozoic Bivalve Entomostraca 



of Canada. Can. Org. Remains, Dec. III., pp. 91-102, pi. XL 



1889. Jones, T. Rupert. On some Palaeozoic Ostracoda from Penn 

 sylvania. American Geologist, Vol. IV., pp. 337-342, with plates, 



1890. Jones, T. Rupert. On some Palaeozoic Ostracoda from 

 North America, etc. Quart. Journ. Geol. Soc. London, Vol. 46, 

 pp. 1-3 1, pis. I-IV. 



1890-gi. Ulrich, E. O. New and Little Known American Palaeo 

 zoic Ostracoda. Journal Cincinnati Society of Natural History, Vol 

 13, pp. 104-137; 173-211, pis. 7-18. 



1897. Ulrich, E. O. Ordovician Ostracoda of Minnesota, in Minn 

 Geol. Surv., Vol. 3, pt. 2, pp. 629-693, pis. XLIII.-XLVI. 



1900. Ulrich, E. O. North American Palaeozoic Ostracoda, I 

 Journ. Cin. Soc. Nat. Hist., XIX., pp. 179-181, pis. VIII. 



1906-08. Ulrich, E. O., and Bassler, R. S. North American 

 Palaeozoic Ostracoda, pts. II and HI. Proceedings of the U. S. 

 National Museum, Vol. XXX., pp. 149-164, pi. XL; and Vol. XXXV., 

 pp. 277-340, pis. XXXVII.-XLIV. 



B. Mesozoic and Cenozoic. 



1886. Jones, T. Rupert. On some Fossil Ostracoda from Colo- 

 rado. Geol. Magazine, n. ser., Decade III., Vol. III., pp. 145- 

 148, pi. IV. 



1893. Jones, T. Rupert. On some Fossil Ostracoda from S. W. 

 Wyoming and from Utah. Geol. Magazine, n. ser.. Decade III., 

 Vol. X., pp. 385-391, Pl- XV. 



1901. Ulrich, E. O. Eocenic Ostracoda of Maryland. Md. Geol. 

 Surv., Eocene Volume. 



