AKT. 4. N. YATSU : 



I. INTRODUCTION. 



Although the adult anatomy of Lingula has been thoroughly 

 studied by many investigators, its embryology has not received 

 the amount of attention which it deserves, owing no doubt to the 

 difficulty of obtaining materials. The observations 1 of McCrady 

 ('60), of Semper ('61), and of Simroth ('97), are but frag- 

 mentary. Brooks ('78) is the only author who has dealt with 

 it with anything like adequacy, but even in his case, older larvae 

 alone were treated. The early history of development has thus 

 remained entirely unknown to this day. 



Lingula anatina Bruguière occurs in great abundance in 

 the neighborhood of the Marine Biological Station at Misaki. 

 The efforts to make the Brachiopod breed in captivity had, 

 however, repeatedly failed there as elsewhere. It was, therefore, 

 by a specially good fortune that during the summers of 1899 and 

 1901 I was enabled to observe the spawning habits and to collect 

 a moderately complete series of the early developmental stages of 

 Lingula. On this the present investigation has been carried out. 

 The work was undertaken at the suggestion of Professor K. 

 Mitsukuri, to whose generous aid I am greatly indebted. My 

 sincere thanks are also due to Professor I. Ijima and Professor 

 S. Watasé for much valuable advice. I wish also to express 

 my obligations to Professor B. Dean of Columbia University, 

 U. S., who during his stay in Japan kindly read the manuscript 

 in one of the stages of its preparation, and suggested many 

 improvements in the language employed. 



1. K. Owen ('35, '53) must have mistaken the blood corpiiïcles of Lingula for the 

 embryos. 



