GANOIDEI. 



I I I 



BIBLIOGRAPHY. 



(88) Knock. "Die Beschr. d. Reise z. Wolga Behufs d. Sterlettbefruchtung." 

 Bull. Soc. Nat. Moscow, 1871. 



(89) A. Kowalevsky, Ph. Owsjannikoff, and N. Wagner. "Die Entwick. 

 d. Store." Vorlauf. Mittheilung. Melanges Biologiques tires du Bulletin d. FAcad. 

 Imp. St Petersbourg, Vol. vil. 1870. 



(90) W.Salensky. "Development of the Sterlet (Acipenser ruthenus)." i Parts. 

 Proceedings of the Society of Naturalists in the imperial University of Kasan. 1 878 and 9 

 (Russian). Part I., abstracted in Hoffmann and Schwalbe's J ' ahresbericht for 1878. 



(91) W. Salensky. " Zur Embryologie d. Ganoiden (Acipenser)." Zoolo- 

 gischer Anzciger, Vol. I., Nos. u, 12, 13. 



LEPIDOSTEUS 1 . 



The ova of Lepidosteus are spherical bodies of about 3 mm. 

 in diameter. They are invested by a tough double membrane, 

 composed of (i) an outer 

 layer of somewhat pyriform 

 bodies, radiately arranged, 

 which appear to be the re- 

 mains of the follicular cells ; 

 and (2) of an inner zona radi- 

 ata, the outer part of which 

 is radiately striated, while the 

 inner part is homogeneous. 



The segmentation, as in 

 the Sturgeon, is complete, 

 but approaches closely the 



meroblastic type. It com- FIG. 58. SURFACE VIEW OF THE OVUM 



mences with a vertical furrow OF LEPIDOSTEUS WITH THE MEMBRANES 



REMOVED ON THE THIRD DAY AFTER IM- 



at the animal pole, extending PREGNATION. 



through about one-fifth of the circumference. Before this furrow 



has proceeded further a second furrow is formed at right angles 



1 Alexander Agassiz was fortunate enough to succeed in procuring and rearing 

 a batch of eggs of this interesting form. He has given an adequate account of the 

 external characters of the post-embryonic stages, and very liberally placed his 

 preserved material of the stages both before and after hatching at Prof. W. K. Parker's 

 and my disposal. The account of the stages prior to hatching is the result of 

 investigations carried on by Professor Parker's son, Mr W. N. Parker, and myself on 

 the material supplied to us by Agassiz. This material was not very satisfactorily 

 preserved, but I trust that our results are not without some interest. 



