24 E. 8. Morse—Classification of Mollusca 
the posterior end of the sac remains open, and the mouth, par- — 
tially inclined that way, receives its food from that end; the 
food being conducted to the mouth by ciliary motion as in the 
three lower classes. The nature of their food is also identical, 
being of an infusorial character, and as such it is obvious that 
masticating organs, or biting plates, such as we find in the two 
higher classes, are not needed. 
So long also as the posterior end of the sac remains open, the 
anus terminates at that end; when this opening becomes closed, } 
as in the higher classes, the anus seeks an outlet through the 
anterior opening, and the mouth, that before received its food | 
from the posterior end of the sac and by ciliary motion, now 
distinctly points the opposite way, and is furnished with the 
proper organs to procure food, the nature of which requires 
separation and trituration ' 
In nearly all the foregoing en he and also the position 
in which I place the Tunicate sac, I am sustained by heat rit- 
ings of eminent naturalists. With the a le poeever, 
y views completely reverse the Weed war poles of the dy, : 
ward's Treatise on Mol- 
correct, they were precisely right. In all my previous attempts 
to homologize the different classes, I had always met with an 
Pp 
them comformable with already received relations, the more I 
am convinced that such relations are wrong; and it is only in 
believing that continued research will but confirm these propo- 
sitions, that I now = = offer them. 
According to the s here advanced, the Brachiopods are 
(1) attached by a roldikeadion from the dorsal area, as in the lower 
Polyzoa, where they lie on the back. (2) In their natural po- 
sition in life, this valve is really uppermost. (8) The process 
aa 
