XIV CLASSIFICATION OF OLEACINID^E. 



vian Island of Neumayr, westward in the mid- American re- 

 gion, or on the Brazil- African continent Archhelenis of von 

 Ihering must be an open question, with the probabilities 

 favoring the latter hypothesis. In any case, it is certain that 

 the American and Eur- African stock have been wholly separ- 

 ated as far back as the end of the Cretaceous period. 



The soft anatomy of Oleacinida has been investigated most 

 extensively by Hermann Strebel, who more or less fully ex- 

 amined Pseudosubulina, Streptostyla, Strebelia, Salasiella 

 and Euglandina. I have dissected part of these groups and 

 a few species of the additional genera Oleacina and Varicella. 

 Simroth has given an account of Poiretia. The genera 

 Spiraxis, Rectoleacina and Oryzosoma are unknown anatomi- 

 cally, and several of the others have been very imperfectly 

 described; consequently no natural classification of all the 

 genera is at present possible. 



The classification of Oleacinidce used by Tryon in Vol. I. 

 of this work was practically that of Pfeiffer's Nomenclator 

 Heliceorum Viventium, published in 1878, with some addi- 

 tional groups introduced by Strebel; yet Tryon was not in- 

 fluenced by the broad methods and spirit of Strebel's work. 

 In the twenty-five years since Strebel's essays appeared, no 

 taxononic work has been done on the group. It is thus to 

 be expected that a new examination of the soft parts and the 

 shells themselves must result in an arrangement of genera 

 and species widely different from that of Pfeiffer and Tryon. 

 The genera now known anatomically may be provisionally 

 grouped as follows. 



a. Radula small, its length contained 8 or more times in that 

 of the shell, the transverse rows of teeth ~but slightly ob- 

 lique. Epiphallus terminating distally in a flagellum. 



Varicella. 



a 1 . Radula large, its length usually more than one-fourth that 

 of the shell, the rows of teeth very oblique, v-shaped. 

 Epiphallus terminating in the vas deferens only. 

 6. Penis terminating in a blind sack. 



c. Penis with an appendix ; labial processes long. 



L&voleacina. 



