E. W. Berry — An American Spirulirostra. 327 



Art. XXX. — An American Spirulirostra; by Edward 



W. Berry. 



In 1906 Emil Bose 1 described certain Tertiary niollus- 

 can faunas from the Isthmus of Tehuantepec in southern 

 Mexico. These faunas as described comprised less than 

 fifty species, and included no Cephalopoda, and the erro- 

 neous conclusion was reached that they indicated a lower 

 Pliocene age. 



Through the courtesy of the Transcontinental Oil Com- 

 pany I have received large collections of invertebrates 

 from Tehuantepec, and it may be definitely stated, that 

 this fauna, imperfectly described by Bose, is a rich trop- 

 ical shallow-water fauna of several hundred species, and 

 is clearly of Miocene age, as was recognized in the field 

 by Dr. Bruce Wade, the paleontologist of the Company. 

 It is hoped, that in the course of time a fully elaborated 

 account of this interesting fauna will be published by one 

 of my students in paleontology. Meanwhile I wish to 

 call attention to one of the more spectacular elements of 

 this fauna. 



I refer to unusually good material of a new species rep- 

 resenting the genus Spirulirostra which constitutes the 

 first record of this interesting genus in the Western 

 Hemisphere. The material is more complete even than 

 the celebrated Spirulirostra bellardi described by d'Or- 

 bigny from the upper Miocene of Superga, near Turin, 

 Italy — a reproduction of d'Orbigny's figures of which 

 have embellished nearly every textbook of conchology and 

 paleontology that has been published between 1842 and 

 the present time. 



This new species from Mexico may be called Spiruli- 

 rostra americana. Upwards of a dozen specimens have 

 been found. These usually represent merely the more 

 resistant guard or rostrum with a part of the included 

 phragmocone, and they are generally much worn by wave 

 action. The best specimen, which is also slightly above 

 the average in size, is scarcely worn, and shows a nearly 

 complete guard with its contained phragmocone, and a 

 large part of a proostracum ; and it is this specimen from 

 which the accompanying illustrations have been drawn. 



1 Bose, E., Bol. Inst. Geol. Mexico, No. 22, 1906. 



