THE SEGMENTATION OF THE EGG OF THE MYXINOID, 



BDELLOSrOMA STOUTI, BASED ON THE DRAWINGS 



OF THE LATE BASHFORD DEAN. 



By Eugene Willis Gudger 



Bibliographer and Associate in Ichthyology 

 American Museum of Natural History 



AND Bertram G. Smith 



Professor of Anatomy 

 New York University 



INTRODUCTION 



The late Bashford Dean, formerly curator of fishes in the American Museum, 

 published in 1899 an extensive memoir' on the external development of this member of 

 the family Myxinidae from material secured in Monterey Bay, California, in August and 

 September, 1896. In this he dealt very briefly with the segmentation of the egg, this 

 section of his paper covering two and a half pages with only five text'figures (four of which 

 are herein reproduced as Text'figures 4, 5, 6, and 7) as illustrations. Of his material he 

 says: — "An . . . examination . . . has afforded an almost complete series of segmenta' 

 tion stages which will enable a detailed consideration of the earliest developmental 

 features. In the present paper the following preliminary account may be given — illus- 

 trated by several text-figures . . . drawn from reconstructions in wax of serial sections." 

 This short section was plainly intended as merely preliminary to a fuller description and 

 discussion of the subject. This is confirmed by his further statement that: — "In these 

 [text-figures made from wax reproductions and reproduced later herein], accordingly, 

 the marginal limits of the germinal area [of these meroblastic eggs] are not so softly shaded 

 as they would appear from direct surface drawings of the segmenting eggs. The lines of 

 cleavage are also somewhat sharper than in the surface drawings of the segmenting eggs 

 which I have in part prepared for lithographic reproduction." From this it is clear that 

 Dean from his fairly abundant material intended to write a paper based on careful and 

 detailed study of the segmentation of the egg of Bdellostoma fully illustrated by figures 

 from his own hand. It is these drawings which are now under consideration. 



Doctor Dean's Bdellostoyna materials, other than slides and alcoholic specimens, 

 consist of a portfolio ot miscellaneous drawings labelled "Bdellostoma 1896-1901," and of 

 four notebooks labelled "Bdellostoma" but undated. In the portfolio we found four 

 mounted plates of drawings containing thirty-four figures showing the blastoderms of 

 eggs in process of segmentation. Of the thirty-four figures, some are duplicate drawings 

 of the same egg or at any rate of the same stage of cleavage, and others are incomplete. 

 From these thirty-four figures we have chosen the twenty-four which are most represen- 



1. On the Embryology of Bdellostoma stouti. A General Account ot Myxinoid Development from the Egg and Segmentation 

 to Hatching. (In Festschritt zum siebensigsten Geburtstag von Carl von KupfFer. Jena, 1899, pp. 221-276, 12 pis., 25 text-figures. J 



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