144 s. HATTA. 



been completed the iir.st «ouiite lies just beliind the audhory vesicle 

 ((Uiv. fig. 26). 



According to Scott, (/. c, p. 160), the segmentation into meta- 

 meres precedes in the Selachians the separaticjn of the proto vertebrae 

 from the lateral plate, but both processes occur simultaneously in 

 Pclrormjzoit. I learn, however, from my sections that PelromyzoH is 

 exactly like the Selachians in this respect. 



Tlie formation of the germinal layers in l\lromiizon as gi\en 

 above accords well with tlie general plan of the dcNclopment of these 

 layers in the A^ertebrata, as shown in Ampliioxus l)y Ilatchek. in Triton 

 and ll(i7ia by Ü. Hertwig, and in Trlonyx and Clenwiijs ])y Mitsukuri. 

 The points of agreement and disagreement with previous writers' on 

 Pelroimizoit as Calberla, Scott, Shipley, and Kupffer liave been 

 incidentally touched upon, in the course of the present paper and need 

 not airain be entered int<j in detail. In the main, mv results a urée best 

 with those of (Adberla. 



Zoological Laboratory, Science College, Dec. 1891.. 



1. I ref>Tet that I have not sceu the work liy Max Schnitze. 



