78 



Echinopluteus transversus mtva forma. 



PI. XI 11. Figs. 1-4. 



Ill llu' material collected by Mr. Blegvad in the West Indies in the 

 early pail ol' lUll there was a luiiiiher ol" specimens dl lh;it most rciiKirk- 

 able Echinoid larva (Fit?. 29) which 1 described in 1912 in the ■Festschrift 

 fiir Sj)enger"i) and which I thought must be the larva of Echinomelra 

 liiciinlcr. That this reference was erroneous I have proved myself by 

 rearing the larva of that b>hinoid from the egg through metamorphosis. 

 It therefore still remains an open (piestion to which Kchinoid this larva 

 belongs. - Meantime I have found in Ihc piaiiklon samples collected in 

 the Indian Ocean on my Expedition to Siam in 1900 a specimen of a larva 



Fig. 20. Echinophilcus Iransi'er.siis, species e. A. "/i- T?-'°Vi- I'"iMure A shows tiic excessive 



length! of Ihe posloral arms, wiiich are not even <|iiite complete here, the point being 



broken in the specimen from which the figure was drawn. 



exactly similar to the Westindian form, and another one was taken there in 

 191 1 on my way to the Pacific. Furthermore two related forms were taken 

 in the (iulf of Panama in 1916, and two more were found in Ihe material 

 collected in Ihe West Indies by Mr. Blegvad and Mr. Fa ye. Thus 1 

 have now no less than six different s|)ecics of this interesting larval form, 

 which I shall designate as Echiuopliilcus Iransix'isus. The species described 

 in the paper quoted above is, together with the one from the Indian Ocean, 

 the most spezialized of all, the other forms showing more or less primitive 

 features. Still they all have so many characteristic features in common 

 that I have deemed it desirable to keep them together under the same 

 name, even though it may seem very probable that they will prove to 

 belong to difTerent genera, but within the same family, beyond doubt. 



This larval type is eminently characteristic through the excessive devel- 

 opment of the postoral arms, while the other arms remain undeveloped, 



') Th. Mortensen. Ober die Larve von Echinomelra hicunter (L.) ('?). Zool. .lalirh. 

 Suppl. XV. 2. Bii. 1!)12, p. 275—88, Taf. 19—20. 



