16 



DK. TH. MORTENSEN, 



postero-lateral rod, which appears to be the part of the skeleton of the 

 Spatangoid larva which affords the best specific characters. Unfor- 

 tunately the only information I can give of it is that to be found in 



Fig. 14. 

 Fig. 14. — Echinoplnteus of Spataiujus 

 purpiireus, three weeks old. 35/1. 



Fig. 15. 

 Fic 15. — Part of the skeleton of the 

 Echinoplutcus of Spatanguspurpureus. 

 Pf Posterior rod. ; pi, postero-lateral 

 rod. 275/1. 



Figure 15. It is seen that its basis is not widened, and that its edges are 

 .serrated. Apparently it will be found to resemble that of the larva of 

 Echinocardium cordatum (cp. Echinodermenlarven der Plankton Ex- 

 jjedition, Taf. IX, 7). 



The total length — processes included — is ca. 3-5 mm., not 6 mm. as 



