24 



latter species has not the peculiar shape of a biconvex lens, and the post- 

 oral arms are not horizontal, and, upon llu- whole, it appears that the 

 larvae of these two forms musl bo very unlike. I'lie liorizontallx diiecUd 

 postoral arms of Eiuidaris Tlwuarsi, which nmst doubtless be mucli 

 longer in the fully formed larvtc, recall the remarkable Kchinoplulvus 

 transversus; were it nol for the ophicephalous pedicellaria^ of the latter, 

 I would think them to belong together. — The few facts brought 

 forward here can only make one the more anxious to get an opportunity 

 of working out the complete development of Eucidaris. That, at least, 

 E. melularia has a similar larval form is very probable. Its eggs are quite 

 similar to those of E. Thonarsi, as 1 was able to ascertain flaring my 

 stay at llilo, Hawaii. Fertilization of this species could, however, nut 

 be undertaken, as I never succeeded in getting a ripe male and female 

 at the same time. 



While the larva of Cidaris cidaris is the only Cidarid-larva hitherto 

 reared to what must be at least very nearly its full shape, it is cjuile |)os- 

 sible that also the larva of another Cidarid, viz. Stiilocidaris af finis (Phil.) 

 is known. As 1 have explained in my paper on "Die Echiniden dcs Mittel- 

 meeres"*) there is some reason to think that the larva figured by .loh. 

 Mil Her in his 7th Memoir on the larva?" and metamorphosis of Echino- 

 derm«, Taf. 1 Fig. 1 — 2, belongs to this Cidarid. not to Spluerechinus, as 

 was hitherto supposed. 



Phyllacanthus parvispinus Ten. Woods. 



PI. V. Figs. 3—4. 



During a short stay at Port .Jackson in the beginning of March 191.5 

 1 found a few specimens of this s])ecies containing ripe genital ])roducts 

 and I succeeded in getting a small culture. The eggs are few in number, 

 rather large, ca. 0.5 mm, of a greenish colour, and they float at the sur- 

 face. The fertilization membrane is very thick, gelatinous, nol sharply 

 limited on the outside. The first division was seen to take place about 

 'A hours after fertilization. As the fertilization was undertaken in the 

 evening the process of the cleavage could not be followed in details. 

 only a very poor light being available. It appeared, however, that the 



cidaris jutpillala. so that 1 liave l)ecii able lo coiinrm that it is really lliis spceics, which was 

 sliulied l)y I'rouho, not llic n\ore common medilenaiieaii form, SIijIih idaris a//inis. which 

 was at the lime Prouho wrote his jiaper nol recofinized as separate from Cidaris ridaris. 



') 'l"h. -Morlensen. Die Kchinideii des Miltelmeeres. Kiiu- revidierle fhersichl der 

 im Mittelnieere lebenden Echiniden mil Bcmerkungen iibcr ncue oder wenifj l)ekaimte For- 

 nien. Mitt. a. d. Zool. Stat. Neapel. 21. 1913. p. 20. 



There is, however, also a possibility that this larva may belong to Genocidaris maculala 

 \. Ag., the larva of this common mediterranean species being also unUnown. 



