44 



fenestrated, riu- vciilrnl transverse rods join with tlieir points hut do 

 not cross one another - at least not in tliis slai^e. 



It should be |)()inted out that tiic \\<ji,u\v of tiiis lai'va is drawn from 

 a preserved specimen, so that it is \ cry j)r()i)al)lc that tlicre is sonic shiink- 

 age in the soft parts of both body and arms. 



Toxopneustes roseus (A. Aji.). 



I'l. VIU. Fig. 7. 



Fertilization of tiiis species was undertaken on November 11th at 

 Taboga, Panama. It was, evidently, at the end of its breeding season, 

 most of the specimens being em])ty. 



The eggs are of the usual small size, transparent, though somewhat 

 yellowish. The cleavage does not present any unusual features. .\t the 

 ase of 21 hours the embrvos show the first rudiments of the skeleton; 

 at the age of two days they have the typical plutcus shape of the first 

 stage. The body skeleton forms a basket structiirc, the posloral rods 

 are fenestrated. — On the following dav the larvse all died, and there was 

 no i)ossibility of getting a new culture. No figures were drawn of the 

 young larvae; since the skeleton has been dissolved in the preserved 

 specimens, there is no reason to give any figure to show the general shape 

 of the larva, which is as usual. 



Although I did thus not succeed in rearing this larva beyond the first 

 stage, I think I can give some iufoiination also of the somewhat more 

 advanced .stage. In a plankton sample from Xovembci- 1*)15 from near 

 Taboga was found the larva represented in IM. VlII Fig. 7. It is almost 

 beyond doubt thai it must l)e the larva of To.i<)i>nciislcs roseus. The regulai- 

 h>chinoids occurring at Taboga are the following: Eucidaiis Thowiisi. 

 Diadciud inexicainini, Asliopijga piilvinaUi, Toxopiieastes roseus, Li/lcrlii- 

 nus panamensis and Evhiuomclra ixai lUunli. Diadema was not ripe at 

 that time and is therefore out of (picstiou: tlic young stages of luicid<uis 

 described above are so dilTerent from this larva Ihat it is hardly imagin- 

 able, how it could develop into a larva like the one in (piestion. The .l.s7/«- 

 pilf/d- and L///rr/H'/)f;.s-larva are (juite difTcrent (sec 1*1. \' Figs. (>- 7 and 

 IM. \'II Fig. 1); also lulunonwlru run Brunii was learcd to the young 

 Fluteus, the body skeleton of which forms a strongly thorny basket 

 structure. Thus To.iopncusles roseus alone remains to which to refei- 

 this larva. 



('haracterislic of this larva is the considerable length of the ventral 

 transverse rods, which are crossing one another and make the median 

 part of the postoral band project as a pair of small lobes, supported 



