75 



the band rising over it — in the preserved specimens at least. The suhoral 

 cavity is very distinct. The body is short, obUquely truncated as in Ech. 

 lucunter. The postoral arms are somewhat unusually long. On the sides 

 of the body the ciUated band reaches far backwards. The pigmentation 

 is not very conspicuous; there is an indication of pigment spots in the 

 point of the arms and scattered red pigment cells over the body. 



No figures can be given of the skeleton on account of its having been al- 

 most dissolved in the preserved specimens ; but I have noticed that the 

 body skeleton forms a comphcate basket structure, the recurrent rod 

 being double; it is not very thorny. The postoral rods are fenestrated. 



As seen in PI. XII. Fig. 2 there are still traces of the skeleton preserved, 

 showing the double recurrent rod, but it is insufficient for giving detail 

 figures. The postoral rods have been restored in the figure, but it is 

 distinctly seen in the specimen that they are fenestrated and also that they 

 are somewhat thorny. 



Echinometra Mathaei (Blv.). 



Fertilization of this species was undertaken repeatedly in April 1915, 

 but never very successfully, only once the young Pluteus-stage being 

 obtained. Moreover, the skeleton has been completely dissolved in the 

 specimens preserved ; no more information can therefore be given than what 

 is found in my notebook, namely that the body skeleton forms a basket 

 structure, very thorny, and very oblique, the recurrent rod being consider- 

 ably shorter than the body rod. — Unfortunately it is not stated in my 

 book, whether the recurrent rod is double as in E. oblonga and lucunter. 

 The postoral rods are fenestrated. The larva is rather much pigmented, 

 almost opaque. 



In view of the fact that de Meijere^) and H. Lym. Clark^) are inchned 

 to regard Ech. oblonga only as an extreme form of Ech. Matlwsi, while 

 Doderlein^) makes it the type of a separate genus (on account of its 

 peculiar triradiate spicules), it is interesting to notice that there appears 

 to be quite a conspicuous difference between the larvae of the two forms, 

 which is decidedly in favour of their being, at least, distinct species. Even 

 in the first cleavage processes I noticed a marked difference between them, 

 the cleavage cells lying much more closely pressed against one another 

 in E. oblonga than in Mathxi (while the eggs did not appear to be different 

 in size or color). On account of the incompleteness of this record of 



') Siboga-Echinoidea 1904, p. 101. 



2). Hawaiian a. otlier Pacific Ecliini. Tlie Pedinidse .... and Eciiinometridae. Mem. 

 Mus. Comp. Zool. XXXIV. 1912, p. 370. 



') Echinojdea d. deutsclien Tiefsee-Expedition. p. 233. 



10* 



