51 



it worth while giving this figure, since otherwise no figure exists of a 

 fully formed larva of a true Strongylocentrotus-species. 



Concerning the four anterior epaulets I may point out that it cannot 

 be decided from the single specimen in hand, whether they have been 

 separated off from the vibratile band or not; in the latter case they will 

 be no true epaulets, but only the band along the vibratile lobes. 



Strongylocentrotus franciscanus, together with the other Californian 

 species S. purpuratus, has been the object of a great many experimental 

 studies, especially by Loeb. In spite of this the larvae of these two species 

 have not been described hitherto in any way adequately; only some out- 

 line figures have been given of the first larval stage for the sake of com- 

 parison with hybrid larvae of the two said species, while no informa- 

 tion at all is given of the later larval stages. But at least we may gather 

 from these papers^) the important information about the larva of Stron- 

 gylocentrotus purpuratus that in its first stage it agrees closely with the 

 larva of S. drabachiensis and pulcherrimus in having a long, clubshaped 

 body rod; there may be an indication of a recurrent rod, much smaller 

 than in franciscanus, and there is, accordingly, no basket-structure. — 

 The species breeds during the winter season. I had therefore no opport- 

 unity myself of studying its development. 



Temnopleurus toreumaticus (Klein). 



PI. X, Fig. 6. PI. XII, Fig. 6. 



Fertilization of this species was undertaken at Misaki on June 25th 

 and again on the 29th, the first culture being unsuccessful. The eggs are 

 very small and transparent. The cleavage and the first developmental 

 processes go very rapidly, so that already after about 12 hours the embryos 

 leave the egg-membrane in the shape of blastulae, and at the age of ca. 

 22 hours the embryos were found to have assumed the Pluteus-shape 

 (PI. Xll, Fig. 6). A conspicuous feature of the young larva is the very 



^) J. Loeb, W. O. R. King & A. R. Moore. Ober Dominanzerscheinungen bei den 

 liybriden Pluteus des Seeigels. Arch. f. Entw. Mechanik. Bd. 29. 1910. p. 354—362. Taf. 

 XI— XII. 



J. Loeb. tJber die Natur der Bastardlarve zwischen dem Echinodermenei (Strongylo- 

 centrotus franciscanus) und Molluskensamen (Chlorostoma funebrale). Arch. f. Entw. Mech. 

 Bd. 26. 1908. p. 476—82. 13 figs. 



J. Loeb. Weitere Versuche iiber heterogene Hybridisation bei Echinodermen. Arch, 

 f. d. ges. Physiologic. Bd. 104. 1904. p. 325—50. 



J. Loeb. Die chemische Entwicklungserregung des tierischen Eies. 1909. (On p. 7, Fig. 

 17 is represented a young Pluteus of Strongyloc. purpuratus). 



A. L. Hagedoorn. On the purely motherly character of the Hybrids produced from the 

 eggs of Strongylocentrotus. Arch. f. Entw. Mechanik. 27. 1909. p. 1 — 20. 



7* 



