414 Dr. E. S. Morse on the Early Stages 



L. — On the Early Stages o/" Terebratulina septentrionalis 

 [Gouthouy). By Edward S. Morse, Ph.D. &c.* 



[Plates XV. & XVI.] 



There is hardly a group among the lower animals (if we 

 consider the relatively small number of species represented by 

 it) that has attracted the attention of so many naturalists as 

 the Brachiopoda. The names of Cuvier, Owen, Vogt, Huxley, 

 Hancock, Gratiolet, Lacaze-Duthiers, Bouchard-Chantereaux, 

 Miiller, Davidson, Carpenter, King, D'Orbigny, and a host of 

 others are sufficient evidence of the interest felt in a group 

 whose organization links them so closely with the past. 



The desire to interpret, through a knowledge of its living- 

 forms, the many species which are now extinct, as well as to 

 ascertain the relations it bears to the other divisions of the 

 animal kingdom — the contemplation of a group whose maxi- 

 mum development in genera and species was attained in the 

 Devonian age, though its representatives are strewn through 

 the rocks of all ages since the dawn of life upon the globe — 

 the remarkable fact that among the earliest forms of organic 

 life known are genera whose species can hardly be distin- 

 guished from present existing forms— all explain the attrac- 

 tions its study has afforded alike to zoologists and palaeonto- 

 logists. 



The splendid memoirs upon the Brachiopoda by some of 

 the authors just mentioned, more particularly those of Albany 

 Hancockf, Vogt, and Gratiolet, offer but little encouragement 

 to one entering the field with the expectation of gleaning any 

 thing new. While, however, the anatomy and histology of the 

 adult animal of several species has been carefully worked up, 

 little or nothing has been done toward elucidating the embryo- 

 logy or the early stages of the class. Fritz Miiller J has given 

 in a short note a description and two figures of what he con- 

 siders an early stage of a species of Discina ; and Lacaze- 

 Duthiers § has made some extremely interesting observa- 

 tions on the embryo of Thecidmm. Apart from these two 

 papers, we know of nothing whatsoever relating either to the 

 embryology or the early stages of the Brachiopoda. The 

 importance and necessity of some information regarding the 

 embryology of these animals has been ui-ged by many writers ; 



* From the ' Memoirs of the Boston Society of Natural History,' vol. ii. 

 Commuuicated by the Author. 



t " On the Organization of the Brachiopoda," Phil. Trans. Roy. Soc. 

 Lond. 1858, vol. cxlviii. part 2. 



J Reichert und Du Bois-Reymond's Archiv fiir Anat., I860, p. 72. 



§ " Histoire de la Thecidie,''^ Ann. des Sc. Nat. ser. 4. tome xv. p. 262. 



