534 THE AMERICAN NATURALIST. [Vol. XXXVII. 



e/iceans, described by Phillippi as F. kieneri Phil., occurs in the 

 modern fauna of the south coast. 1 This may be merely a reversed 

 F. eliccans, but it seems more likely that it was independently 

 derived from the reversed Miocene type just mentioned (F. obfilo- 

 sum). 



The table at the end of the article indicates the probable 

 genetic relationship- of the species under discussion. 



Variations jn the spines of adult Fulgur caricum. 



Normally the spines of F. caricum are uniform in the adult, but 

 individual variation is quite marked here. The final whorls of 

 this species are generally marked by a series of color bands, or 

 strong growth lines, which indicate a resting stage following a 

 growth period. Each growth period begins with a non-spinous 

 shoulder condition, and the spine begins to form only in the last 

 half or last third of the period. At the end of the period the 

 spine is at its maximum, and opens forward. With the begin- 

 ning of the next growth period, the spine is closed anteriorly, or 

 more rarely, is abandoned abruptly and floored over at the base, 

 remaining open in front. Not infrequently the period is short- 

 ened, when the spine is only partially or not at all developed. 

 This may perhaps be a pathologic condition. Sometimes 

 the spine makes its appearance only toward the end of its 

 normal period, and hence is small. This character, due to 

 retardation, repeats the ancestral state of the spines in types 

 like F. maximum var. A Conr. (compare F. rapum), where it 

 was normal. Again, a period may be lengthened, when the 

 spine will be larger than the normal. Such is the normal con- 

 dition in F. candelabrum, where each period constitutes a third 



