186 



but fairly deep, reaching down to the upper edge of the stomach or even 

 some distance beyond. Fine, redbrown pigment grains are scattered all 

 over the body. The length of the fully formed larva is ca. 0,5 6 mm. 

 Although metamorphosis was not completed, the development pro- 

 ceeded far enough to show definitely the important fact that this larva 

 has no Brachiolaria-stage; this is what was to be expected from the 

 evidence of the only other Astropecten-species, the metamorphosis of which 

 has been studied, viz. Astropecten aranciaca (the "Bipinnaria von Triest" 

 of Joh. Muller, IV. Abhandl. Taf. V.). 



Astropecten polyacanthus Muller & Troschel. 



A few specimens of this species, containing fairly ripe sexual products, 

 were obtained at Misaki on the 18th of June 1914, and fertilization was 



undertaken, resulting, however, in only a small cul- 

 ture, the eggs not being as ripe as desirable, and 

 therefore only comparatively few being fertilized. 

 The sperma, as usual, had to be treated with NaOH 

 in order to obtain active movement of the sperma- 

 tozoa. Only a few of the embryos survived the ga- 

 strula stage, and only a single specimen reached far 

 enough (at the age of 10 days) to show the characters 

 of the larvae. Moreover, this specimen was abnormal, 

 its right side remaining in a rudimentary condition. 

 But the left side of this larva was typically devel- 

 oped, and, in spite of all, this specimen (Fig. 97) 

 Fig. 97. Abnormal larva makes it sufficiently evident that the larva of A. 



of Astropecten poiyacan- 



thus, 10 days old. 1<l5 /i. polyacanthus is so closely alike that of A. scopanus 



that it will be hard to distinguish them. The fact 

 that the postoral band is straight in the A. polyacanthus-larva, while it 

 is concave in the larva of A. scoparius, is not likely to be a reliable disting- 

 uishing character. The poly acanthus-larva differs, however, from the A. 

 scoparius-larva in being devoid of pigment. It was also found to be con- 

 siderably more active in its movements than the latter species. 



Asterina (Patiria) pectinifera (Muller & Troschel). 



PI. XXXIII, Figs. 12. 

 Th. Morten sen. On the development of some Japanese Echinoderms. p. 550. 



This strikingly beautiful starfish occurs fairly abundantly on the rocky 

 shores near the Biological Station at Misaki. Fertilization was undertaken 

 in the end of May and the beginning of June, but the cultures obtained 



