202 
what sort of instruction is to be expected from his 
labours. 
Testaceological writers are to be classed as 
follows : 
I. Those who have written generally of 
Conchology. 
IL Those who have described a single genus, 
family, or species. 
III. Those who have described the shells of 
certain parts of the globe. 
IV. Those who have described museums or 
collections of shells. 
V. Those w^ho have described minute shells, 
microscopic subjects. 
VI. Those who have detailed the wonders of 
the science. 
VII. Those who have written on the anatomy 
of testaceous worms. 
VIII. Those who have written on their phy- 
siology. 
IX. Those who have invented or followed a 
systematical arrangement of shells. 
X. Those vrho have commented on the works 
of others. 
XL Those who have published plates illus- 
trating Conchology. 
