131 



and has been reconstructed in free hand in the figure. It is then quite 

 possible that the stomach really fills the whole space between the skeletal 

 rods. Also the anterior vibratile band was indiscernible. — The pigment- 

 ation is characteristic, consisting of fairly large pigment cells, scattered 

 along the body rods. 



Only one specimen of this very interesting larva was found, off Jolo, 

 20/III, 1914. That it belongs to one of the Ophiothrichidse seems fairly 

 certain; in all probabiUty it does, however, not belong to the genus Ophio- 

 thrix itself, but rather to one of the other genera within that family. 



Ophiopluteus of Ophiocoma. 



Ophiopluteus Henseni Mrtsn. 



In a note on the "Embryology of Ophiocoma echinata''^) Caswell 

 Grave reports having reared the larva of this species, but gives no descript- 



Flg. 57. Larva of Ophiocoma echinata, ll^/j days old. After a sketch from life 

 by Caswell Grave, lOA^III. 1897. 



ion or figures of it, only the first embryonal stages being described. A full 

 report was never published. On my applying to Professor Grave concern- 

 ing this larva he most kindly sent me a sketch of the larva at the age 

 of 11 ^/a days for free disposal. Also slides containing some young larvae 

 were sent me. The sketch proved especially valuable, making it possible 

 to identify the Ophiocoma-larva. with full certainty; it is reproduced in a 

 reduced scale in Fig. 57. I beg to express my deep gratitude to Professor 

 Grave for his kindness in supplying me with this important information. 

 In the said paper Grave mentions that the eggs "after being fertilized 

 threw about themselves a tough prickly egg membrane", as is also shown 

 in figs. 1 — 2 of that paper. I would suggest that this pecuhar membrane, 

 otherwise unknown in Ophiurids, is a special adaptation, serving as a 



1) Johns Hopkins Univ. Circulars. Vol. 18. 1898. p. 6—7. 



17* 



