96 ART. 4. — N. YATSU : 



arm-sinus has lost its communication with the body cavity ; the 

 latter has given off into the arm-apparatus a pair of finger-like 

 processes ; the lacunar system around the oesophagus and in the 

 epistome has made its appearance. 



XII. CONCLUSION. 

 a. Observations of Previous writers. 



To show how far our knowledge of the development of 

 Brachiopoda has advanced up to the present day, it will he, I 

 think, not superfluous to devote the following few pages to a 

 brief history of the embryology of Brachiopoda. I then shall 

 enter upon a comparison of the developmental processes of our 

 Lingula with other forms. 



The first investigator to describe the " embryos " of Lingula 

 anatina Brug. was Bichard Owen ('35) ('53, p. 387), but 

 judging from his figures it is very obvious that what were taken 

 for embryos of the animal by Owen must have been blood 

 corpuscles. 



The next author is Oscar Schmidt ('54), who gave an 

 account of an embryo of the Norwegian Terebratula. It is inter- 

 esting that in this paper there is given for the first time a 

 description of a true Brachiopod-embryo. 



Shortly after this Gratiolet ('60), in a somewhat extended 

 memoir on the Brachiopod appears to have mistaken the proble- 

 matical elements of the coelomic fluid known as " Spindle-bodies " 

 for young Lingula developing in the body cavity as the result 

 of self-fertilization. 



