150 PROCEEDINGS OF THE ACADEMY OF [April, 



NEW MOLLUSCA OF THE SANTO DOMINGAN OLIGOCENE. 

 BY H. A. PILSBRY AND C. W. JOHNSON. 



The authors have had a revision of the fossils of Santo Domingo 

 and Haiti, chiefly contained in the William M. Gabb collection, in 

 preparation for some years. The work is now completed; but as 

 some months must elapse before the illustrations can be published, 

 advance descriptions are here given of most of the new forms. 



The age of the Santo Domingan beds covered by the collections of 

 Heneken and Gabb has been the subject of some uncertainty; but 

 it appears that the lower bed or beds, containing Orthaulax, are nearly 

 or quite equivalent to the Orthaulax pugnax zone of the Oligocene of 

 Tampa Bay, while the upper beds, furnishing most of the fossils, 

 are uppermost Oligocene, synchronous with the upper beds (Gatun 

 formation) of the Canal Zone. We have found no evidence of Plio- 

 cene or other beds between the Upper Oligocene and the Pleistocene. 



Illustrations of the species here described will appear in the com- 

 plete report, now awaiting publication. 



AOTEONIDiE. 

 Aoteon subtornatilis n. sp. 



Actceon tornatilis Linn., Gabb, Trans. Amer. Philos, Soc, XV, p. 245. 



Shell similar to A. tornatilis of Europe in size and form, but as 

 coarsely sculptured over the whole body-whorl as that species is 

 on the base. There are about 35 subequal spiral grooves on the last 

 whorl, cut into square or oblong pits by narrow vertical lamellae, 

 the grooves separated by flat-topped ridges which are wider than 

 the intervals except on the base, where they become narrow, no 

 longer flat-topped, and about equal in width to the intervening 

 grooves. Length 17, diam. 8.4, length of aperture 12 mm. 



This form was referred to A. tornatilis by Gabb, but it differs in 

 having the sculpture coarser and equally developed over the whole 

 body-whorl, not finer and fainter in the middle as in the well-known 

 European species. 



Type No. 3183. 



Acteooina subbuUata "• sp. 



This species is almost identical with A. bullata (Kilner) in form 



