OLIGOCENE ECHINODERMATA. 171 



The periproct is relatively small, about 3 or 4 millimeters in length, subclliptical to sub- 

 rhomboidal, transverse. ; and located relatively high up on tbe posterior surface, at the top of the 

 rather high posterior truncation, beneath a rounded, transverse, somewhat protruding expansion 

 of the test. 



Related forms. — Cassidulus georgiensis is readily separated from the other representatives of 

 the genus from American deposits. In some features it resembles Cassidulus carolinensis, but 

 it can be distinguished by its flatter under surface, more obtusely rounded and more angular pos- 

 terior margin, higher and more oblique posterior truncation, and smaller periproct. Of foreign 

 forms G. georgiensis resembles some forms of Pygorhynchus grignonensis (Defiance) Agassiz from 

 the Eocene of France, but can be separated by its more oblique posterior truncation, more 

 angular posterior margin, and higher placed periproct. 



Localities.- — 'Flint River, near Bainbridge, Baker County, and 2+ miles north of Cuthbert, 

 Ga.; Alabama (exact location unknown) . 



Geologic horizon. — Vicksburg formation, lower Oligocene. Possibly also Jackson formation, 

 upper Eocene. The matrix is a yellow mass of foraminiferal remains. 



Collections. — U. S. National Museum (164347); Yale University. 



Cassidulus (Pygorhynchus) gouldii (Bouve). 

 Plate LXXIX, figures 3a-d; Plate LXXX, figures la-f, 2a-d. 



Pygorhynchus gouldii Bouve, 1846, Boston Soc. Nat. History Proc, vol. 2, p. 192. 



Pygorhynchus gouldii Bouve, 1847, Am. Jour. Sci, 2d ser., vol. 3, p. 437. 



Pygorhynchus gouldii Bouve, 1847, Annals and Mag. Nat. History, 1st ser., vol. 20, p. 142. 



Nucleolites mortoni Conrad, 1850, Acad. Nat. Sci. Philadelphia Jour., 2d ser., vol. 2, p. 40, PI. I, fig. 11. 



Pygorhynchus gouldii Bouve, 1851, Boston Soc. Nat. History Proc, vol. 4, pp. 2-4, two figures in text. 



Pygorhynchus gouldii Desor, 1858, Synopsis des echinides fossiles, p. 299. 



Ravenelia gouldii McOrady, 1859, Elliott Soc. Nat. History Charleston Proc, vol. 1, pp. 282, 283, no figure. 



Pygorhynchus gouldii Dujardin and Hupe, 1862, Histoirenat. zoophytes echinodermes, p. 585. 



Pygorhynchus gouldii Conrad, 1865, Acad. Nat. Sci. Philadelphia Proc, p. 74. 



Pygorhynchus gouldii Conrad, 1866, Smithsonian Misc. Coll., vol. 7 (200), p. 22. 



Pygorhynchus gouldii Agassiz, 1S83, Mus. Comp. Zoology Mem., vol. 10, No. 1, p. 91. 



Pygorhynchus gouldii Cotteau, 1888, Paleontologie francaise, Echinides eocenes, vol. 1, p. 550. 



Pygrohynchus gouldii Clark, 1891, Johns Hopkins Univ. Circ, vol. 10, No. 87, p. 77. 



Nucleolites mortoni Boyle, 1893, U. S. Geol. Survey Bull. 102, p. 200. 



Pygorhynchus gouldii Stefanini, 1911, Soc. geol. italiana Boll., vol. 30, p. 696. 



Determinative characters. — Test irregularly subcorneal, broadly ovate, broadest back of 

 middle; variable in height; margin flat along the sides, angular at the ends, sharply angular under 

 periproct; upper surface elevated anteriorly, more or less obliquely flattened and depressed 

 posteriorly, under surface slightly concave longitudinally. Apex excentric anteriorly. Ambu- 

 lacral areas broad in petaloidal region, narrow beyond; petals long, rather sharply pointed at 

 both ends, almost closing. Apical system excentric anteriorly or subcentral. Peristome trans- 

 versely elongate, excentric anteriorly, more so than the apical system, with floscelle. Periproct 

 elliptical, transverse, supramarginal, at the top of a shallow groove, and beneath an ovei hanging 

 expansion of the test. 



Dimensions. — Specimen A (type): Length 52 millimeters; width 49 millimeters; height 25 

 millimeters. Specimen B: Length 35 millimeters; width 33 millimeters; height 18 millimeters. 

 Specimen C (unusually high): Length 38 millimeters; width 36 millimeters; height 24 milli- 

 meters. 



Description. — The species was reported and an excellent description given as early as 1S46 

 by T. T. Bouve of Boston, whose type specimen the writer has had the privilege of studying. 

 The form, which though one of the best known in the literature was formerly considered rather 

 rare, has been shown by recent collections made by the members of the United States Geological 

 Survey and others to be one of the most abundant of American Cenozoic echinoids. It is 

 especially abundant in Florida, where it has been found at many localities. The species is very 

 variable, its extreme specimens differing so much in a number of details that they might be 



