1896.] NEW YORK ACADEMY OF SCIENCES. 137 
STaTeD MEETING. 
March 9th, 1896. 
In the absence of regular business, the Section of Biology at 
once organized, Pror. Curtis in the chair, Dr. Dyar, Secretary 
pro tem. Inthe absence of the Secretary, the reading of the 
minutes was omitted. 
Mr. F. B. Sumner read the following paper: 
THE VARIETAL TREE OF A PHILIPPINE PUL- 
MONATE. 
By Francis B. SuMNER. 
An expedition recently sent to the Philippine Islands, under 
the direction of the Minnesota Academy of Sciences, procured 
among other things of great value some most interesting sets 
of land shells. These, in addition to their value to the syste- 
matic conchologist, present some striking examples of the phe- 
nomena of variation. 
The accompanying figure (see Plate VI., at end of volume) 
represents a varietal tree, constructed by the writer from shells of 
the pulmonate Cochlostyla ovoidea, obtained on Masbate Island. 
The genus Cochlostyla is a very large one, comprising, as stated 
by Cooke (Cambridge Natural History, Vol. I., “‘“Mollusca’’) no 
less than 247 species. Many of the species are of extreme vari- 
ability, serving as an excellent illustration of the law laid down 
by Darwin that the larger genera present as a rule the most 
variable species. 
This species varies in shape, size and color. In length, adult 
specimens were found varying from 1.05 inches to 1.80 inches. 
Differences in shape I determined by comparing the ratio of 
length to breadth. In the stoutest specimens, length = 1.76 x 
breadth. In the slenderest, length = 2.29 x breadth. 
But by far the most striking differences are those of color and 
ornamentation. These are fairly well, although by no means 
perfectly represented by the figure.* 
On comparing any one of the color varieties of this species 
with any other, I found it possible to bridge over the gap by 
*T wish to here express my indebtedness to Prof. Henry F. Nachtrieb, for the loan 
of uae set, and to Dr. Edward Leaming, for his care in securing a satisfactory photo- 
graph. 
