40 AMERICAN JOURNAL 



tended as a statement of the case, than as a criticism upon the 

 special views put forward by that gentleman. HoAvever, he has 

 seen fit to regard them in the latter light, and has complained 

 that they were not in the nature of impartial criticism.* I sin- 

 cerely regret that such should be his feeling, and can only state 

 in defence, that they were not intended as a criticism, but as a 

 statement of certain important characteristics of the various 



oups compared, and hence could not include much reference to 

 the many trivial and irrelevant facts which he had brought for- 

 ward in support of his theories. 



I propose, however, at present to meet him on his own ground, 

 and to give at the same time as thorough a statement of the case 

 from my point of view, and as impartial review of all the facts 

 as the case will admit. 



As it is impossible to solve an algebraic problem without affix- 

 ing a definite value to some of its terms, so it is impossible to 

 fairly discuss any theory until the ground upon which the differ- 

 ent parties stand, is clearly defined. 



Prof. Morse has advanced two theories, but has mainly di- 

 rected his efforts to the sustentation of the second of them. They 

 are, 1st. The brachiopods present a comprehensive type. 2d. 

 The brachiopods are not mollusks, but a subdivision of the anne- 

 lids. 



It seems to me that these two statements are irreconcilable. 



In tbe first view I am inclined to agree with Prof. Morse to a 

 certain extent. In the second, I am entirely unable to agree 

 with him. 



It is evident that much, if not all, the discussion must turn 

 upon the point, what is a mollusk or inolluscoid, and what is 

 an annelid, or, in general terms, a worm. 



I have repeatedly desired Prof. Morse to define these two types 

 from his standpoint, and he has never responded. Is it, there- 

 fore, to be supposed that he has no clear ideas upon these sub- 

 jects, or that he fears that any definition would so expose the 

 weakness of his theory as to insure its immediate rejection ? It 

 would, perhaps, be hardly fair to draw such conclusions. 



For my own part, I am quite willing to define my views and 

 position with regard to the question in detail ; though I am as 

 conscious that there are others who might state the case far 

 more ably than myself. If any one person, by some miraculous 

 gift, were able to study all the forms which have lived upon the 

 earth since it first became habitable, and that person was also 

 gifted with the mental attributes necessary for the comprehension 



* Silliman's Am. Journ., Sci. and Arts, Feb., 1871, p. 136. 



