No. 432.] STUDIES OF GASTROPODA. 945 
may be made by means of a system of analysis in which 
the individual is the unit of comparison, because its life in all 
its phases, morphological and physiological, healthy or patho- 
logical, embryo, larva, adolescent, adult, and old (ontogeny), 
correlates with the morphological and physiological history 
of the group to which it belongs (phylogeny)." 
PALZEONTOLOGICAL LABORATORY, 
COLUMBIA UNIVERSITY. 
