1914.] NATURAL SCIENCES OF PHILADELPHIA. 567 



MORPHOLOGIC SEQUENCES IN THE CANALICULATE FULGURS. 

 BY BURNETT SMITH. 



The Tertiary and Recent gastropods which are usually assigned 

 to the genus Fulgur or to the genera Fulgur and Sycotypus have been 

 studied on several occasions in the endeavor to. clear up the phylo- 

 genetic relationships of the different species. Inexact methods of 

 collecting, poorly preserved material, and uncertainty of stratigraphic 

 relations have perhaps contributed in no small degree to the con- 

 flicting interpretations which have resulted. In spite of the attention 

 which these forms have attracted, no detailed morphologic work has, 

 so far, been attempted in the group. The purpose of the present 

 paper is to record some of the changes exhibited by the canaliculate 

 division of the genus when traced throughout its geological and 

 geographical range. 



The following notes have been prepared after an examination of 

 Avell-preserved specimens whose localities and horizons are in most 

 cases known to have been determined with considerable accuracy. 

 Museum sets of individuals falling well within a single specific diagno- 

 sis have been omitted whenever there was a suspicion that they were 

 derived from more than one locality or from more than one horizon. 

 It is recognized, however, that the amount of collecting necessary 

 for a final settlement of these problems of phylogeny is far beyond 

 the resources and the time of any one individual. Conclusions 

 reached in these notes are therefore submitted with the full realization 

 that they are preliminary in character and limited in scope. 



In even so simple a structure as the gastropod shell there are too 

 many features to be taken in and appreciated at a single glance, and 

 when a number of gradational forms are viewed together it is seldom 

 possible to retain any definite mental image in passing from one 

 extreme to the other of a morphologic sequence. True, it can be 

 seen by the most casual inspection that many species are closely 

 allied, but to say how they are allied is by no means an easy matter. 

 The chief obstacles encountered in such work are those presented 

 (1) by multiplicity of morphologic characters, (2) by the inadequacy 

 of words to express the requisite shades of meaning, and (3) by the 

 difficulty of representing a transitional ontogenetic stage in a diagram. 



