125 



articular end of the anchor-plates is in these species unusually 

 constant. In the other five species of the genus the articular end 

 of the plates is so varying that it is often exceedingly difficult to 

 say which shape is the most characteristic. Furthermore the shape 

 of the plates themselves is so constant that the length-width indices 

 give a rather good character for separating the species from each 

 other. The table below shows how much they differ. The measure- 

 ments are given in microns. 



Species 



Anchors 



Anchor-plates 



Length 



Width 



L : W 



Length 



Width 



L : W 



spectabilis . . 



glabra 



clarki 



150—300 

 270—280 

 150—250 



185—200 

 160—170 

 90—150 



0,66—0,74 

 0,60—0,66 

 0,55—0,60 



220—250 

 180—240 

 150—200 



180—185 

 140—180 

 140—180 



0,74—0,81 

 0,76—0,81 

 0,90—0,93 





Ophe ode soma serpentina (Johs. Müller). 



Synapta serpentina. Johs. Müller. 1850. Anatomische Studien über 

 die Echinodermen, pag. 132. The figures of the 

 calcareous deposits are found in Johs. Müller: Über 

 den Bau der Echinodermen, Pl. IV fig. 17, Pl. IX fig. 5. 



Euapta serpentina. 0stergren. 1898. Das System der Synaptiden, 

 pag. 113. 



Opheodesoma serpentina. 1907. Fisher. The Hawaiian Holothurians, 

 pag. 725. 



Opheodesoma serpentina. Clark. 1908. The Apod. Holothurians, p. 76. 

 Amboina. 10.11.1922. The shore by low-water mark, among Thalassia. 

 5 specimens. 



The specimens at hand measure from 30 to 50 cm in length, 

 The colour is bluish-grey with white spots due to large heaps of 

 miliary granules. They have 15 tentacles, each with 20 — 25 pairs of 

 free digits. On the oral disk there are eye-spots. The cartilaginous 

 ring is well developed and the processes on the anterior margin 

 of the calcareous ring (Fig. 4. 2) are united by a thick menbrane. 

 The calcareous ring itself is distinctly green and the radial processes 

 are perforated for the nerves. On the circular canal there are 

 numerous polian vesicles and madreporic canals. The gonads are 

 long and branched. The intestine has a loop and on the mesenteries 

 there are numerous ciliated funnels of the usual shape. 



