Morse. | 318 [March 19, 
and afterwards republished in Silliman’s Journal. The fact that in 
that paper the Brachiopoda were turned up side down, and end for 
end, shows the violent methods resulting from faith in accepted views. 
It is a simple matter of justice to myself that I make this confession, 
and I may also say that my studies of the Brachiopoda have been 
made, not for the purpose of describing new species or genera, to 
show their geographical distribution, or to tabulate the number of 
species known, but simply and solely, to determine their affinities ; 
and that some weight may attach to the radical views here advanced, 
I may, with satisfaction, state that my investigations on the subject 
embrace a series of observations on the anatomy and early stages, 
of Discina, from an immense mass of material in alcohol fur- 
nished me by Prof. Verrill. I have also carefully studied living Lin- 
gula, Rynchonella, and Terebratulina, and the early stages and embry- 
ology, of the latter. 
Some of these investigations have already been published, and I had 
hoped to present them all before publishing this paper, but as some 
time will be required to prepare the results, and the necessary plates 
on Lingulaand Discina, I am reluctantly compelled to present this 
first. 
INTRODUCTORY CONSIDERATIONS. 
The changes here proposed in the removal of the Brachiopoda 
from the Mollusca, and their association with the Vermes, make 
necessary a comparison between the Mollusca, as now restricted, and 
the Vermes. 
Many naturalists now hold the opinion that the Mollusca are 
descended from the Vermes. Indeed, it would seem from the rapidly 
accumulating data that the Vermes underlie the whole animal king- 
dom, with the exception of Protozoa. Only on this hypothesis, that 
the Mollusca are derived from the Vermes, can we understand the 
otherwise strange assemblage of characters displayed by such Mol- 
lusks as Chiton, Dentalium, Pneudermodon. 
In our comparisons we are justified in selecting as typical Mollusca! 
those groups which have remained unchanged the longest. 
1 We leave out of consideration the Polyzoa, since they are not only related to the 
Brachiopoda, but because they are regarded as worms by Leuckart, Gegenbaur, and 
many others, and also the Tunicates, regarded by many naturalists as forming the 
base of the vertebrate series; others placing them with the Vermes, and by all 
separated from the Mollusca proper. 
