43° TRANSACTIONS OF THE WAGNER FREE 



the notch thickened, the fascicle represented by a shallow groove; margin of 

 the shell reflecting the external sculpture. Alt. 3.0; Ion. 5.5 ; diam. 4.0 mm.. 



This pretty little species is nearest allied to E. Rollandi Fischer of the 

 recent fauna, but the character of the sculpture through its various mutations 

 is perceptibly different and the shell is smaller and proportionally more 

 elevated. 



It is respectfully dedicated to Mr. H, A. Pilsbry, to whom we owe an 

 important revision of the Fissurellidce , among other valuable contributions ta 

 the science. 



Order PTEROPODA. 



Suborder THECOSOMATA. 



This group was inadvertently overlooked in its proper connection, as it 

 should have preceded the order OpistJiobranchiata (Part I., p. 14), to the 

 members of which this group is more or less intimately related. As there can 

 be no reasonable doubt that species of Pteropoda date from the very early- 

 Paleozoic rocks, I am unable to follow the superficial conclusions of some 

 recent morphologists who would subordinate the group into separate sections 

 of the later Opistliobranchiata. 



Very few genuine Pteropods have been described from our Tertiaries. 

 Lesueur, in 1829, figured (Walnut Hills Fossil Shells, pi. i., fig. 12, a, b) a 

 form which has since been described by Meyer under the name of Styliola 

 hastata, which, however, belongs to the genus Creseis. 



Gabb named a Miocene fossil from Santo Domingo Planorbella (not of 

 Haldeman) which has subsequently received the name of Valvatella from 

 Morch (jion Gray), and Valvatina Borneman. The species P. imitans i.s 

 possibly related to Oxygyriis, or may be the Planorboid stage of a Cceatm like 

 the V. parisiensis of the Paris basin, and not a Pteropod. 



From the Eocene of the Claiborne sands come Creseis hastata Meyer 

 (also found in the Vicksburgian and Red Bluff beds), C ? niniba and C ? ebla 

 De Gregorio. The last two look like fragments of Dentalia, and the typo- 

 graphical errors of the references are so bad that it seems impossible to tell 

 which figures are referred to. At all events, more information is necessary 

 before either shell can be regarded as a Pteropod. 



From the Jacksonian we have Creseis simplex Meyer (as StyHola) and a 

 form, perhaps not a Pteropod, which Meyer has named Styliola corpidenta. If 

 a Pteropod, it should be referred to Creseis. 



From the Miocene of Santo Domingo, Gabb has described Cavolinia 

 (Diacria) bistdcata, Cleodora {Balantiuni) midtdatuvi and Styliola stdcifera, 

 which is a genuine Styliola. From the Miocene of Costa Rica he reports 

 Creseis bicostata under the name of Styliola. He has also described, as a 

 " Triptera," Vaginella clavata, from the Miocene of California. Professor 

 Holmes has described from the Post-Pliocene of South Carolina a Cavolinia 



