CLASSIFICATION OF UROCOPTID^E. XXIX 



nized, particularly in Holospira, Epirobia and Anisospira. 

 Indeed, the structure of the axis of the shell was for the first 

 time utilized in classification, in Strebel's work. 



The classification of Pfeiffer-Clessins' Nomenclator Heli- 

 ceorum Viventium (1878) is no advance upon that of Fischer 

 and Crosse. Berendtia, Holospira, Eucalodium and Ccelo- 

 centrum form two subfamilies of Achatinida; and are fol- 

 lowed by the family Cylindrettida, where are placed the 

 genera Leia, Pineria, Macroceramus and Cylindrella; the 

 last a very heterogeneous group. 



Nothing further bearing upon the taxonomy of Urocop- 

 tidce appeared for some years. In 1895 (Nautilus, ix, pp. 

 50, 51), Dr. W. H. Ball offered a "Synopsis of the sub- 

 divisions of Holospira and some related genera ' ' ( Ccelocen- 

 trum and Eucalodium), in which the work of Strebel upon 

 the internal characters of the shells was supplemented and 

 extended. 



In 1898 Pilsbry and Vanatta published "Materials toward 

 a Natural Classification of the Cylindrelloid Snails " (Proc. 

 A. N. S. Phila., pp. 264-286). The generic nomenclature was 

 critically reviewed and revised in this paper, and a new 

 classification of Antillean species was based upon the struc- 

 ture of the radula and axis. While the main features of 

 this classification are retained in the present work, further 

 anatomical investigation has resulted in some notable changes, 

 as in the case of Archegocoptis, Spirostemma, Tetrentodon, 

 Microceramus, etc. 



CLASSIFICATION OF UROCOPTID^:. 



In the differentiation of the teeth of the radula we have 

 an excellent basis for classification of the Urocoptincz, the 

 more useful because this organ is generally preserved in dry 

 cabinet specimens of the shells. The teeth are so complex 

 that, provided their morphology is rightly understood, the 

 phytogenies based thereon cannot be far wrong. At the same 

 time, there can be no doubt that new data of a good deal of 

 value will be gained by a study of the rest of the soft anat- 

 omy, particularly the genitalia and free muscles. The rela- 



