778 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



It differs from Idmonm radioata in the nature of its ovicells; Kirkpatrick's 

 species belongs to another family. 



The difference between the fossil fragments and Idmonea atlantica Johnston, 

 1847, is quite difficult to determine most of the time. It is preferable not to deter- 

 mine the specimens which are not very well preserved. They differ from it in a 

 lesser divergence of the fascicles on the median line and chiefly in the interfascicular 

 distance which is less than 0.40 (and very rarely more than 0.40 mm.). 



In its dorsal it resembles Idmonea sloani, but differs from it in its much 

 greater interfascicular distance (0.40 and not 0.20 mm.). 



The dorsal of this species corresponds well to Lonsdale's description of 

 Idmonea commiscens; but wie have never observed "the intermingling of mouths" 

 mentioned and figured by that author. On the contrary, his Idmonea 14 of 

 Rock Bridge conforms more to the present species. 



Occurrence. Middle Jacksonian: Wilmington. North Carolina (very com- 

 mon) ; Eutaw Springs, South Carolina (rare) ; 18 miles west of Wrightsville, 

 Johnston County, Georgia (rare) ; near Lenuds Ferry. South Carolina (common). 



Upper Jacksonian (Ocala limestone) : Chipola River east of Marianna. Jack- 

 son County, Florida (very rare) ; west bank Sepulga River, Escambia County, 

 Alabama (rare) ; below Plant System railroad wharf, Bainbridge, Georgia (very 

 rare). 



Vicksburgian (Red Bluff clay) : Seven and one-half miles southwest of Bladen 

 Springs, Alabama (rare). 



Vicksburgian (Marianna limestone) : One mile north of Monroeville, Alabama 

 (very common) ; near Claiborne. Monroe County, Alabama (very rare). 



Cotypes.O&t. Nos. 65414-65416, U.S.N.M. 



IDMONEA ATLANTICA Johnston, 1847. 



Plate 140, figs. 1-13. 



1847. Idmonea atlantica (FORBES Mss.) JOHNSTON, A History of the British Zoophtyes, 

 2 ed., p. 278, pi. 48, figs. 3, 3. 



1856. Idmonea atlantica BUSK, Polyzon collected by Mr. McAudrew on the coasts of 

 Norway and Finland in 1856, Annals and Magazine Natural History, ser. 2, vol. 18, 

 p. 34, pi. 1. figs. 6o-e. 



1858. Idmonea atlantica BUSK, Zoophytology, On some Maderian Polyzoa, Quarterly Jour- 

 nal Microscopical Science, vol. 6, p. 128, pi. 18, fig. 5. 



1875. Idmonea atlantica (part) BUSK, Catalogue of Marine Polyzoa in the collection of 

 the British Museum, pt. 3, Cyclostomata, p. 11. 



1880. Idnimiea atlantica HINCKS, History of British Marine Polyzoa, p. 451, pi. 65, figs. 1-4. 



1886. Idmonea atlantica (part) BUSK, Report on the Polyzoa collected by H. M. S. Chal- 

 lenger during the years 1873-1876, vol. 50, p. 10. 



1890. Idmonea atlantica ORTMANN, Archiv. fur Naturgeschichte. vol. 1, Heft 1, p. 58, pi. 4, 

 figs. 20o, 6 (var. disticha Ortmann). 



1894. Idmonea atlantica LEVINSEN, Mosdyr. Zoologica Dauica (Danske Dyr.), vol. 4. 



1895. Idmonea atlantica (det. R. Kirkpatrick) THURSTON, Ramesvaram Island and Fauna 



G. Manaar. Madras Government Museum, Bull. 3, p. 131. 



