THE BRITISH FOSSIL BRACHIOPODA. 311 



embryonic character, remarking that the difference in this respect between the Brachi- 

 opoda and Acephala is as great as between the latter and the Gasteropoda. 



It would not be possible here to enter into the numerous and elaborate details given 

 by those zoologists in support of their views, and the reader must therefore refer for more 

 ample information to Prof. Morse's several papers upon the subject, and especially to the 

 one " On the Systematic Position of the Brachiopoda," published in the ' Proceedings of 

 the Boston Society of Natural History,' vol. xv, 1873, as well as to that of Kowalevsky in 

 1875, and to which we have already referred. 



The second memoir of the Russian zoologist, says A. Agassiz, " is a very complete 

 history of the development of the Brachiopods, strikingly in accordance with the views of 

 Morse on the affinities of the Brachiopods with the Annelids. The homology between 

 the early embryonic stages of Argiope with the known Annelid larva is most remarkable ; 

 and the resemblance between some of the stages of Argiope figured by Kowalevsky, and 

 the corresponding stages of growth of the so-called Loven type of development among the 

 Annelids is complete. The number of segments is less, but otherwise the main structural 

 features show a closeness of agreement which will make it difficult for Conchologists 

 hereafter to claim Brachiopoda as their special property. The identity in the ulterior 

 mode of growth between the embryo of Argiope and of Balanoglossus, in the Tornaria 

 stage, is still more striking ; we can follow the changes undergone by Argiope, while 

 it passes through its Tornaria-stage, if we may so call it, and becomes gradually, by 

 mere modification of the topography of its organs, transferred into a minute pedunculated 

 Brachiopod, differing as far from the Tornaria-stage of Argiope as the young Balano- 

 glossus differs from the free-swimming Tornaria. In fact the whole development of Argiope 

 is a remarkable combination of the Loven and Tornaria types of development among 

 Worms. Kowalevsky's paper also includes the history of a less vermiform type of develop- 

 ment, — that of Thecidium and of Terebratula, in which the observations of Kowalevsky 

 fully agree with the previous well-known memoirs of Lacaze-Duthiers on Thecidium, and 

 Morse on Terebratulina ; and it certainly is a striking proof of the sagacity of Morse to 

 have announced so positively, from the history of American Brachiopoda alone, the 

 vermiform affinities of the Brachiopoda, proved, by the development of Argiope, in Kowa- 

 levsky's paper." 



No one can doubt that the Brachiopods and Amphitrites possess several important 

 characters in common, after perusing the admirable observations upon the subject 

 contained in Prof. Morse's memoir ; but at the same time, as was remarked to me by 

 Prof. Verrill, almost any invertebrate group may be annelidelized by overrating certain 

 points of its affinities ; and it seems to me that one must not place entire confidence in 

 any classification which is founded, to so great an extent, on embryological character. 



The shell, so important a feature in all the Brachiopods, but absent in Worms, is 

 considered by some zoologists, who contend for the worm affinities, to be a character of 

 but small importance, aDd they appear to lose sight of the great differences that exist 



