161 



The median processes are not so large as in species a, and set with oiily 

 few thorns along their outer sides. The anterolateral rods are much more 

 thorny than in species a (Fig. 87); the postoral and posterodorsal rods as 

 in the preceding species. The length of the posterolateral arms is only 

 about 3 times the body length, the other arms as in the preceding 

 species. 



Only two specimens of this species were found, in the Gulf of Panama, 

 off the island of Taboga, in December 1915. 



S 



S 



Fig. 87. Skeleton of Ophiopluteus arcifer, species b. ^'"/i- A. Part of anterolateral rod, 



B. part of posterolateral rod; the adoral side of both is to the left. C. Body skeleton. The 



processes from the transverse rods are restored, being broken in the specimen, and are 



represented in a more upright position than normal. 



Species c. (PI. XXVI, Fig. 3). This species is nearest to species b, but 

 differs from it in the character of the posterolateral rods, which have 

 fewer, small thorns along their outer side, and not in their whole length, 

 while those along the inner side are larger and continue until the point; 

 they ar-e partly (mainly in the lower part of the arm) somewhat spinulose. 

 The rods of the other arms are almost as in species b. The median processes 

 from the transverse rods are shorter than in that species (Fig. 88). The 

 posterolateral arms are about five times the body length. 



One specimen was taken at 17° 47' N. 70° 51' W., l/II. 1911. (H. Bleg- 

 vad). 



This species recalls to some degree 0. bimaculatus (Job. Miiller), but 

 differs conspicuously from it in the presence of thorns along the outer side 

 of the posterolateral rods and in the much greater length of the median 

 processes from the transverse rods. Unfortunately, the only specimen in 

 hand does not give any evidence, whether the development of the Ophi- 



21 



