45 



distinction from D. armata, it may be pointed out that D. malayensis shows no exceptional 

 development of nematocysts in the aboral endoderm of the column, nor do its marginal tentacles 

 present a quadrangular form in section. Van Beneden's examples of D. inermis were all in a 

 decidedly earlier stage of development than the younger examples of D. malayensis, and a 

 comparison of the arrangement of the tentacles and mesenteries in the two forms is impossible. 

 The section of a marginal tentacle which van Beneden figures does not show the dense 

 crowding of the nuclei on the lateral surfaces which is so marked in D. malayensis, the aboral 

 band is of an entirely different character and the abundance of coarsely granular gland cells 

 throughout both the lateral and aboral areas is quite unlike what occurs in the malayan form. 

 On account of these differences it seems advisable to regard the two forms as distinct. The 

 example of D. elcgans is even younger than those of D. inermis, but its distinctness from 

 malayensis ma)' be accepted on the basis upon which van Beneden separates it from the other 

 forms described by him, namely, on the occurrence of large nematocysts with a spiral thread. 

 These do not occur in D. malayensis. 



Gravier's D. bencdeni (1904), notwithstanding that its tentacles and mesenteries were 

 but little in excess numerically of those of the older examples of D. malayensis, is evidently 

 considerably more advanced in development, and it is difficult to say to what extent the 

 differences seen in the structure of the mesenteries in the two forms may be due to this fact. 

 It is possible that later stages of D. malayensis may also show two couples of acontiferous 

 mesenteries and a further development of the deuterocnemes until they resemble those of D. 

 bencdeni in arrangement. Unfortunately Gravier makes no statement as to the presence or 

 absence of a differentiation of the tentacular ectoderm. It seems preferable, in the face of so 

 much uncertainty, to regard the malayan form as distinct for the present. 



It is not improbable that D. viridis described by Verrill (1898) may be identical with 

 one of the forms described by van Beneden, D. digitata possibly, as Verrill himself suggests. 

 The description which has been given of it is, hower," too inadequate for the determination of 

 its specific status, no account being furnished of its structural peculiarities. 



Finally, it does not appear probable that D. malayensis can be identified with any of 

 the forms recently described by Senna (1907). Of these D. mammillata, captured in the Pacific 

 to the north of the Galapagos Islands, differs in lacking the differentiation of the ectoderm of 

 the tentacles, while the other three forms, D. discors, D. tardiva and D. prcccox, all from the 

 Bay of Bengal, differ in the fact that notwithstanding that they possess sixteen marginal tentacles 

 they show no indication of the development of labials, a condition in marked contrast to what 

 occurs in D. malayensis. 



In addition to the forms described above empty tubes of Cerianthids were taken at the 

 followinsjf stations : 



ö 



Stat. 213. Saleyer anchorage and surroundings. 



Stat. 302. Lat. io°27'.qS., long. I23°28'.7E., near Rotti Island. 216 metres. 



Stat. 313. Anchorage east of Dangar Besar, Saleh Bay. 



Stat. ? 



45 



