778 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
It differs from Idmonea radioata in the nature of its ovicells; Kirkpatrick’s 
species belongs to another family. 
The difference between the fossil fragments and Idmonea atlantica Johnston. 
1817, 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 we have never observed “the intermingling of mouths” 
mentioned and figured by that author. On the contrary, his Idmonea 14 of 
Bock Bridge conforms more to the present species. 
0 commence. — 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. — Cat. Nos. 6541U65416, U.S.N.M. 
IDMONEA ATLANTICA Johnston, 1847. 
Plate 140, figs. 1-13. 
1S47. Idmonea atlantica (Forbes Mss.) .Tohnston, A History of the British Zoophtyes, 
2 ed., p. 278, pi. 48, figs. 3, 3. 
1856. Idmonea atlantica Busk, Polyzoa collected by Mr. McAndrew on the coasts of 
Norway and Finland in 1856, Annals and Magazine Natural History, ser. 2, vol. 18, 
p. 34, pi. 1, figs. 6a-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. Idmonea 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. fiir Naturgesehichte, vol. 1, Heft 1, p. 58, pi. 4, 
figs. 20a, l) (var. disticha Ortmann). 
1894. Idmonea atlantica Levinsen, Mosdyr. Zoologica Danica (Danske Dyr.), vol. 4. 
1895. Idmonea atlantica (det. R. Kirkpatrick) Thurston, Ramesvaram Island and Fauna 
G. Manaar, Madras Government Museum, Bull. 3, p. 131. 
