Brooks.] 234 [February 2, 



be supposed, however, that the veliger can be traced back to any- 

 existing form of Polyzoon, or even to any Order of this Class. In 

 some respects its affinities are with the Hippocrepia, in others they 

 are with the Cheilostomata, and in still others they are with Rhab- 

 dopleura, and they therefore indicate that the common ancestral type 

 of the Mollusca was, not a true Polyzoon, but simply a polyzoon-like 

 form. A lack of agreement in points of detail is therefore no more 

 than we should anticipate. In answer to the second objection, that 

 the Polyzoa multiply by budding, we may refer to the well known 

 law, that agamic vegetative multiplication is antagonistic to high 

 evolution, and is accordingly replaced by true sexual reproduction in 

 the higher forms of all classes of animals; as its presence, if it oc- 

 curred in any of the true Mollusca, could not be regarded as proof 

 of an affinity to the Polyzoa, its absence does not disprove such 

 affinity. No one will attach much importance to the remaining ob- 

 jection, that the Polyzoa are fixed; in fact those which are developed 

 from statoblasts are at first free and swim by means of the cilia of the 

 lophophore. 



The similarity between the Polyzoa and true Mollusca, in general 

 plan of structure, has long been recognized, but the attempts to con- 

 nect the two groups through the Lamellibranchs are so evidently 

 incorrect that, led by the unquestionable affinity of the Polyzoa and 

 Brachiopods to the Vermes, many zoologists are now inclined to sep- 

 arate these lower forms from the Mollusca proper. As soon as 

 we recognize that the Lamellibranchs are not to be regarded as 

 typical Mollusca, and that all of the latter are to be traced back 

 to a "Veliger" all difficulty seems to disappear, and it becomes 

 plain, not only that the Mollusca and Molluscoida are related, but 

 that they are connected so closely, that the advisability of such a 

 division is very doubtful. We also obtain, at the same time, an ex- 

 planation of the worm-like early stages of the embryo, exhibited by so 

 many of the true Mollusca. The belief, so firmly supported by nearly 

 all zoologists a few years since, that the various branches of the ani- 

 mal kingdom are absolutely independent of each other, has been al- 

 most entirely overthrown by the accumulation of new facts, and the 

 constantly increasing tendency to examine them in their bearing upon 

 the theory of the evolution of life; and the union or junction of the 

 Vermes and the Mollusca, in some manner, has already found a num- 

 ber of advocates. 



Prof. Morse, by his investigations upon the anatomy and embryol- 







