64 



dorsal side. There are no epaulets. The arms are of medium length, fairly 

 broad. The pigmentation consists of scattered red pigment cells ; no pro- 

 minent pigment spots in the point of the arms. 



Regarding the skeleton full information cannot be given, because it 

 has been dissolved in all the specimens preserved. In my notes from the 

 observation of the living specimens it is stated that the posterodorsal 

 rod is fenestrated, as may also be ascertained from one of the young spec- 

 imens with the skeleton preserved, showing these rods in beginning for- 

 mation. It is very regrettable that I have forgot to state anything about 

 the posterior transverse rod. That this rod is present can, however, not 

 be doubted, partly because the shape of the posterior end of the larva 

 is in conformity with that of other larvae possessing this skeletal rod, 

 partly because in one of the specimens preserved traces of this rod 

 and other parts of the skeleton - - are distinct, made up by the organic 

 matrix of the calcareous substance. Judging from this specimen - - as 

 also from the fact that nothing is said about this skeletal part in my 

 notes --it would appear that the ends of this rod are simply dichotomous, 

 probably the upper branch the longer. 



Some few of the abnormal larvae in the cultures of this species were so 

 remarkable that I have thought it worth while to mention and figure them 

 (PI. X, Figs. 4 5). They are quite flat, with the arms radiating horizont- 

 ally. In the middle of the flat body are seen the rudimentary stomach and 

 mouth. These remarkable forms might possibly indicate that this 

 species would be a favourable object for experimental studies. 



Heliocidaris tuberculata (Lamk.) 



PI. VI, Fig. 3. PI. XI, Figs. 12. 



Th. Mortensen. On the development of some Japanese Echinoderms. p. 545. (Toxo- 

 cidaris tuberculatus.) 



This species, which occurs abundantly on the rocky shores near the 

 Biological Station at Misaki, was found to be sexually ripe early in the 

 summer, and artificial fertilization was undertaken on May 22nd. The 

 cleavage is total and regular; developmental processes are not passing 

 very rapidly. Swimming blastulee were found 20 hours, gastrulae 24 hours 

 after fertilization. At the age of 30 hours the skeleton had begun to form, 

 and at the age of two days the embryos had assumed the shape of small 

 plutei. On the eleventh day the posterodorsal arms had begun to form; 

 at the age of 24 days the larva had the posterodorsal and preoral arms 

 fully developed, while there was as yet no transformation of the body 

 skeleton; at the age of 5 weeks the larvae were found to have begun meta- 

 morphosis and thus reached their full shape. As only few larvae remained 



