1902.] CONKLIN — EMliRYOLOGY OF A BRACHIOPOD. 43 



the so-called ''segments " of the larva are not true segments, as 

 Kowalevsky supposed, but are mere folds in the body wall. 



The papers by Beecher ('91, '92, '93) on the development of 

 brachiopods deal almost entirely with the developmental changes 

 which occur in the shell and not with the general embryology. 

 Beecher has proposed a very interesting and important classification 

 of the brachiopods based on the developmental characters of the 

 shell; since however the present work deals only with the early 

 embryology, we need not further consider Beecher's work here. 



2. Material, — For the material which has formed the basis of 

 this study I desire at the outset to express my profound obligations 

 to my friend Dr. Edward G. Gardiner, of Wood's Holl, Mass. Dr. 

 Gardiner had collected the material (which consists of about thirty 

 different stages in the early embryology of Terebratuli7ia septeritri- 

 onalisy forming a fairly complete series from the unsegmented egg 

 up to the beginning of the metamorphosis) at Eastport, Me., during 

 the early summer of 1894. For various reasons he was prevented 

 from making an immediate study of this material, and when in the 

 summer of 1898 in conversation with him I expressed my desire to 

 study the cell lineage of a brachiopod, he graciously offered me the 

 material which he had collected with the request that I should use 

 it in any way I might see fit. I soon found that it would be impos- 

 sible to work out the cell lineage, not only because of a lack of 

 sufficient number of cleavage stages, but also and chiefly because 

 of the great difficulties which the material itself offered ; the eggs 

 were quite opaque and, except in a few cases, it was impossible to 

 render the nuclei visible in preparations of the entire egg ; the 

 cleavage was almost entirely equal and I was unable to find any 

 constant landmarks which might be used in orientation, and finally 

 the cleavage was found to be more or less irregular and inconstant. 

 I was compelled therefore to abandon the plan to study the cell 

 lineage of Terebratulina and the material was laid aside, until a few 

 months ago I found opportunity to again take up this subject with 

 the view of working out the early development of this interesting 

 animal in as great detail as the material would allow. 



3. Methods.— K\\ the material was, I believe, preserved in Per- 

 enyi's fluid, and while the general form and size of the embryo 

 as a whole, and also of its constituent cells and nuclei, has been 

 faithfully preserved, every trace of the cilia, which according to 

 Morse ('71-73) cover the surface and line the alimentary tract and 



