ox THE PROCESS OF GASTRULATIOX IX CHELOXIA. 263 



Postscript. 



The foreo'oino- article was nearly finished in January of this year. 

 I made an extract of it in the early part of tliat month and sent it to 

 the Afiafoinisdier Anzeiijcr as a preliminary notice.* As I was giving 

 linal t(Ki('hes to tlie article I received from Dr. Ludwig Will an article 

 of his own entitled '' Die Anhuie der Keimblatt er heim (rech) " (Zool. 

 Jahrhilrlier ; Ahth. f. Anat. v. Oui., \ I Baml 1 Heft). As I men- 

 tion in a previous page, I was not under the circumstances able to 

 make full use of Dr. Will's paper, but inserted remarks on it mostly 

 in footnotes. The foreo'oino- article has since then ])een Ivin«- readv 

 for the press, but its publication was greatly delayed, owing to various 

 extraneous circumstances. Wlien it was at last to be put in the prin- 

 ter's hands, I received a second article by Dr. Will : '"'Die Anlage der 

 Keimhläfter hei der menoquiNi,schen Snmjifschildkröte" {ZooJ. JuhrJnlcher : 

 Ahth. f. Anat. u. Ont., V] Band, 3 u. 4 Heft). As it is too late to go 

 over my article again in the light of the facts brought out by Dr. 

 Will, I have decided to add here as a j)ostscript a few remarks on 

 Dr. Wills two papers, as well as on some other articles whicli have 

 appeared recently. 



Will's observations on the two species, Platydacty 1 us face- 

 tan us, Sdireih. iiud Cistudo lutaria, Gesn. coincide throughout. 

 They, I am glad to see, agree also in many essential points with the 

 results I have brought out in this and pre\ious contributions. There 

 are however, several points on which we diifer and some of these, it 

 must l)e confessed, are by no means insignificant. 



1 . According to Will, a stage in which a sickle is present precedes 

 the establishment of the primitive plate in both the species. Since receiv- 



* Published in Anat. Anz., VIII Jahrg., No. 1^1 13. 



