206 PROCEEDINGS OF THE PALEONTOLOGICAL SOCIETY 



defined. Raphiophorus Angelin could not be separated satisfactorily from 

 Ampyx, but Lonehodomus of the same authority proved easily and constantly 

 distinguishable by differences in the facial suture and in the anterior margin 

 of the cephalon. 



A new genus, Ampyxina, is proposed for small Ampyxida 3 with small and 

 very short rostral spine, obovate glabella, a small pair of isolated posterior 

 lateral glabellar lobes, and four or five thoracic segments. The pygidium also 

 differs from that of Ampyx and Lonehodomus in wanting the thick, beveled 

 and striated posterior edge. In Ampyx the second and third pairs of lateral 

 glabellar lobes often are rather well developed and partly separated from the 

 middle lobe, but the posterior pair is seldom well defined and never isolated. 

 Six species of the new genus are known, only one of which has been described 

 and figured, and this without either a generic or specific name. The descrip- 

 tion and figures referred to were published in 1909, by R. R. Rowley, in "The 

 Geology of Pike County," Missouri Bureau of Geology and Mines, second series, 

 volume 8, page 60, plate 15, figures 12-14. The species is not uncommon in the 

 basal part of the Maquoketa shale west of Louisiana, Missouri, and along the 

 Mississippi bank two or three miles above Thebes, Illinois. I propose now to 

 call it Ampyxina bassleri n. sp., and to designate it provisionally as the geno- 

 type of Ampyxina. The other species are all older — Lower Trenton and Upper 

 Chazyan. One occurs with Cryptolithus n. sp. in the Viola limestone in Okla- 

 homa, another in the basal 10 feet of the Martinsburg shale at Chambersburg, 

 Pennsylvania, and three others in subcrystalline limestone lying just beneath 

 the Athens shale, near Blacksburg and Saltville, Virginia, and near Albany 

 and other places in Tennessee. One of the last three may be the same as 

 Raphiophorus powelli Raymond. 



The genera mainly concerned in these studies are Agnostus, Ampyx, Loneho- 

 domus, Ampyxina, Trinueleus, Cryptolithus, Harpes, and Eoharpesf. The spe- 

 cies and varieties of each have been most critically determined, and as thus 

 conceived have proved themselves of great value as guide fossils in correlating 

 the Chazyan and Mohawkian formations in the Appalachian region. Publica- 

 tion of the species will proceed as opportunities offer. 



Under the following title the author brought out the fact that the 

 foraminifera hitherto supposed to be extremely variable are in reality not 

 so at all, for a close study of both fossil and recent species has shown 

 much of this so-called variation to l)e due either to unrecognized stages 

 in development, the peculiar alternation of generations developed in this 

 group, or to the lack of close discrimination of specific characters. 



LIMITS OF VARIATIONS IX FORAMIXIFERA 

 BY J. A. CUSHMAN 



Aii interesting paper describing the paleontological work being done 

 in the Gulf Coast oil fields by the oil companies located at Houston, 

 Texas, was then presented by Miss Esther E. Richards for the author. 



