160 



banded appearance, when seen from the ventral or the dorsal side. Near 

 their base they have a few small thorns along the outer side, and also the 

 body rod generally has a few small thorns. The end rods are provided with 

 several small branches at the point. The transverse rods are hardly widened 

 at the point, but end in a number of very short thorns. The median pro- 

 cesses, which proceed from the transverse rods of the same side, some- 

 times the left, sometimes the right, are very long, slightly curved and irre- 

 gularly thorny along the outer side (Figs. 85, 86). The postoral and postero- 



Fig. 86. Skeleton of Ophiopluieus arcifer, species a. 290^1. Letters as in fig. 85. 



dorsal rods have small, bilaterally arranged thorns, the anterolateral rods 

 have thorns only along the outer side in their outer part. — The postero- 

 lateral arms are about 4 times the body length. 



This species was found S. of Koh Chuen, in the Gulf of Siam, 3/II1. 

 1900 (1 specimen), in the Malacca Strait (101°12' E. 2° 45' X. 30/XI. 1899 

 (3 specimens) and off Jolo, 20/III. 1914 (5 specimens). 



Species b. (PI. XXVI, Fig. 2). The main difference between this spe- 

 cies and the preceding one consists in the posterolateral rods being here 

 provided with thorns along their outer and their inner side, not along the 

 ventral and dorsal sides. The thorns on the outer side are irregular, slightly 

 branched, those along the inner side simple, with the point bent a little 

 forward. The end rods have only one side branch at the point and the 

 transverse rods are provided with only few, short prominences at the point 



