466 SYSTEMATIC PALEONTOLOGY 



Genus ANOMALINA d'Oibigny. 

 The genus Anomalina embraces a small section of Planorhulince 

 forms which become so symmetrically convoluted that both sides of the 

 shell are similar and the type becomes a true umbilicated nautiloid 

 organism. This perfect symmetry does not always attain and d'Orbigny 

 used the word to apply to two different types, one of which was a nearly 

 equilateral compressed, subnautiloid Planorhulina while the other was 

 plano-convex with sunken umbilicus. The forms are closely allied to 

 Truncatulina and the distinction between the two is not very clear. It 

 is unfortunate to still retain the name, but as it has some difference in 

 method of growth, perhaps it is well to use the name making it to in- 

 clude all truly nautiloid forms which are symmetrical and with cen- 

 trally located aperture. 



Anomalina grosserugosa (Giimbel). 

 Plate CXXXI, Fig. 11. 



Truncatuli7ia groxserugoxa Giimbel, 1868, Abhaud. d. k. bayer. Akad. Wiss., ii, cl, 

 voL X, p. 660, pL ii, tig. 104, a, b. 



Description. — Test nautiloid, very coarsely porous; pores larger and 

 more numerous upon the inferior surface; both sides convex; umbilici 

 distinct; peripheral margin round; chambers large, inflated, septal 

 lines nearly straight, depressed, aperture situated on inner margin, 

 medial. 



GiimbeFs specimens were from the Eocene of the Bavarian Alps. In 

 present oceans the species seems to occur sporadically at different locali- 

 ties and at various depths down to 2000 fathoms. 



Occurrence. — Choptank Formation. Peach Blossom Creek. Cal- 

 vert Formation. Chesapeake Beach. 



Collection. — Maryland Geological Survey. 



Genus ROTALIA Lamarck. 



The genus Rotalia forms but a small division of the series of Rota- 

 LiDiE forms. The walls of the test are finely perforate while the allied 

 genus Planorhulina has coarsely perforate walls. 



The general type is that of a turbinate spire which in typical forms 

 like R. beccarii is nearly equally convex on both sides. Again by some 



