106 ART. 4. N. YATSU : 



resembles Fritz Müller's figure for more closely than Bloch- 

 mann's. The dorsal shell, 410/^ and 468,« in longitudinal and 

 transverse diameters respectively, is of a pale yellowish brown 

 and is a little darker around the margins. The ventral shell is 

 much smaller than the dorsal and of the same color. The mantle 

 a little proximal to its margin is tinted \vitli somewhat large 

 brownish pigment granules, while the rest of it is almost color- 

 less. The arm-apparatus is yellowish and the body proper is of 

 a similar but lighter color. 



The largest seta?, 318/', are longer than those in the larva 

 figured by Blochmann, and almost equal in length to those from 

 Desterro. These seta? (PI. VI., Fig. 90 b) end in a short hookless 

 portion different from the larva? examined by Bloch mann. The 

 tips of the seta? next to the last pair are also provided with 

 hooks. The anteriormost pair are segmented at the lower third 

 of their length, as shown, but not described in the right pos- 

 teriormost seta of Blochmann's figure (Taf. XXXL, Fig. 1). 

 Other seta? belonging to the dorsal valve terminate, in an in- 

 wardly directed hook. Fritz Müller describes and figures a 

 pair of eve spots (13/« and 75/< in diameter). Blochmann could 

 not make them out in his preserved material. But the apparent 

 absence of these structures seemed to him of little important in 

 comparing his specimens with those of Fritz Müller : " da sie 

 voraussichtlich durch den Alkohol verschwunden sind," (p. 424). 

 Though the larva I obtained was at the same stage as those 

 from Desterro, yet I could find no pigment spots at all. Their 

 presence or absence, therefore, probably depends upon the specific 

 difference. The otocysts, it should be noted, are quite circular 

 and situated much more posteriorly than those in Fritz Müller's 

 figure. They are of the same structure as those found in the 



