91 



larvae, where it is always found in a horizontal position ; but the fact that 

 there is a piece exactly corresponding to it on the ventral side makes the 

 homology more doubtful. The question must remain unsettled for the 

 present. 



Species f (PL XIII, Figs. 3 — 4, Textfigure 36). One specimen was 

 taken off Minicoy (Maldive Islands; 73° E, T N.; 26/IV. 1900), another in 

 the Bay of Bengal (89° E. 6° N. ; 5/1. 1914). Both specimens are in begin- 

 ing metamorphosis; in both of them the postoral arms are broken, so that 

 their length cannot be ascertained; the remaining piece of one of them is 



Fig. 36. Skeleton of Echinopluteus transversus, species f. Seen from the dorsal side. ^'Vi- 



Letters as in Fig. 34. 



6 mm long. There is evidently no reason to doubt that they will prove to be 

 of about the same length as in species e. The two species are so very closely 

 alike that it is hardly possible from the scanty material available of the 

 species from the Indian Ocean to point out specific differences. That 

 they are, however, really different species is evident from the fact that 

 there are no species of regular Echinoids known to occur both in the West 

 Indian Sea and the Indian Ocean. To enter on a detailed description of 

 the present species seems entirely unnecessary; reference to the figures 

 must be sufficient. 



The interesting problem to which Echinoids these remarkable larvae 

 must be referred now needs some discussion. As mentioned above I came 

 to the result, when describing the first of these larvae, the species e, that 

 it was probably the larva of Echinometra lucunter. The fact that it 

 has in the metamorphosis-stages ophicephalous pedicellarise of the type 



12* 



