7fi 



Iheir (ioveloi)UK'iil Hic qiu'slioii caiinol, o\ course, be regarded as settled; 

 but there is reason to expect that a complete study of their development 

 will show Ihem lo be (juite distinct. 



Echinonietra van Brunti A.Ag. 



i'tilili/.atioii ol this species was tried repeatedJN in the beginning of 

 November 1915 at Taboga, Panama, but always with poor success, it 

 being at the end of ils breeding season. Some of the embryos reached the 

 v(ning Phi tens stage. In the few preserved s|)ecimens the skeleton has been 

 dissolved. No remarks about its structure being found in my notebook, 

 I can only state from memory thai the body skeleton forms a basket 

 structure, but wiu'lher Ihe reeurrenl rod is double or nol. unfortunately, 

 iiiusl remain uncertain. The body is very obliquely truncated. 



Colobocentrotus atratus (Limi.) 



PI. XII, Figs. 4^.'). 



This species occurs in great numbers on the rocky coasts of Hawaii, 

 near Hilo, always in places exposed to the most violent surf. Fertilization 

 was undertaken on April 4th; the culture proved successful. About the 

 early develoi)ment stages I have only noticed that gastrulation had taken 

 place at the age of 24 hours and that the young Pluteus stage was reached 

 nil the second day. The larvae developed normally for about two weeks, 

 wiieii all died away. New fertilization was then undertaken, but with 

 poor lesull, it being about the end of its breeding season. Information 

 can thus be given only of the first larval stage, and, moreover, only in- 

 complete, the skeleton having been completely dissolved in all tiie pre- 

 served specimens. (There was no possibility of making drawings from the 

 living specimens). 



The shape of the larva in the first stage is quite characteristic on account 

 ol the unusual width of the posterior end (PI. Nil, Fig. 5). A sketch made 

 from a living specimen shows that the skeleton passes close to the stomach, 

 tile posterior end ol the body being thus nuicli broader than tiie su])porting 

 skeletal structure. The body is otherwise short, oblicpiely truncate as in the 

 luiunonu'lra larva. The postoral band has a downward sinuation at each 

 side, which indicates the presence of ciliated lobes; on the sides of the body 

 the vibralile l)and goes down almost to the posterior end, which fact, 

 combined with the unusual width of the posterior end, indicates the pre- 

 sence of posterolateral processes in the luUy formed larva. The postoral 

 amis long, diverging, rather broad (probably somewhat broader than 

 shown in the figure). The suboral cavity is very deep, with a Uttle eleva- 



