200 HYATT, 



The unquestioning manner with which I take up these 

 views may excite some surprise, but they are founded up- 

 on facts which calmed all the doubts I at first entertained, 

 and satisfied me entirely of their correctness. Mr. Morse's 

 paper, entitled "A Classification of the Mollmca based on the 

 principle of Cephalization" fully illustrates the homologies, 

 as well, also, as the general plan of that subkingdom. 



Mr. Morse has, also, done me the honor of quoting from 

 my manuscript the term Saccata as a new name for the 

 Mollusca. Since it has been so auspiciously introduced to 

 science, and, as such a definitive term seems to be needed 

 to give uniformity and completeness to the nomenclature 

 of the four plans, I shall make no further excuse for its em- 

 ployment in the future. 



BIBLIOGRAPHY AND CLASSIFICATION. 



There is no bibliography of the Phylactolasmata, or in 

 fact of the Fresh-water Polyzoa taken together, as far as 

 our own country is concerned, but, in Europe, they have, 

 from the time of Trembley,* their discoverer, attracted much 

 attention, and the list of works, that may be consulted with 

 profit, is extensive. The principal among these are the 

 writings of Dumortier and Van Beneden, Professor All- 



accomplished draughtsman, and with all the interest of a zoologist and 

 personal friend. I am indebted to him both for this, and for many other 

 favors that have rendered it possible for me to publish at an early date. 

 In fact, my only regret, in connection with this article, is, that a gen- 

 tleman of such acknowledged ability, whose time is important to science, 

 should not be able to devote it to his own original investigations. 



The lenses employed were made especially for the purpose by Rob- 

 ert B. Tolles, of Canastota, N. Y. The one half inch objective having 

 an angle of 175 and one fifth of an inch working distance was especi- 

 ally well suited for the examination of living animals. 



Mr. J. F. Richardson, of Portland, executed the engraving of the 

 plates with the same skill he has shown in other scientific works, and 

 with more than usual care. 



The wood cuts are very large for a black ground, and, being printed 

 directly from the wood, required all the skill and patience of Mr. Hol- 

 land to produce accurate impressions. 



*Memoire pour servir a 1'histoire d'un genre des polypes d'eau douce. 

 1744. 



