141 



side and Ihen. durini^ growth, tnuist'orred to the ventral side, as was 

 stated by Ludwig.i) 



Species b. (PI. XW, r'ii>. 2). liiis species is characteristic mainly by 

 its remarkably shorl posLerolateral arms, which are shorter than the 

 anterolateral arms, and also broader, Ihe vibratile band along them being 

 distinctly broader llian on liu- ollu'i- arms. The posterior edge of the body 

 is more rounded than in species a, quite semicircular, the body skeleton 

 not at all projecting beyond the line fornied by the posterolateral rods. 

 The body is very shorl and broad, though perhaps hardly so low as shown 

 in the figure; especially the fronlal area may l)e somewhat higher in the 

 living specimens. — The skeleton (P"ig. 66, C) differs only very little from 

 that of species a. The transverse rods are slightly widened at the end, 

 and the end rods appear to dider soincwlial in the shape of their thorny 

 outgrowths. 



Only two specimens, both in a poor stale of preservation, are at hand, 

 from the Oulf of Aden (12 48' N. 50 23' K. 27/Xll. 13) and from off the 

 East end of Sokotra (28/XlI. 13). Both specimens agree in liie characters 

 pointed out, so that it seems beyond doubl that this is a separate species, 

 not an individual abnormahty. It should especially be emphasized thai 

 there is no doubl regarding the peculiar character of the posterolateral 

 arms; the skeletal rod is complete, not broken, and although none of the 

 two specimens are so far in their development as to have begun meta- 

 morphosis, there is no reason to expect that the posterolateral arms would 

 ultimately reach the same length as in the other species. 



The fact that the body skeleton (l"ig. 66, C) has the recurrent rod devel- 

 oped only on one side is, of course, an individual abnormality; in the other 

 specimen there is also a slight abnormality in the recurrent rod, bul in 

 this case it is on the right side. 



Species c. (Fl. XXIV, Fig. 2). This third species has a considerable 

 resemblance to species a. The posterolateral arms are long as in thai species, 

 but more divergent; the arms are, upon the whole, relatively shorter than 

 in species a. Also the body is shorter and broadei-. and the frontal area 

 is mainly confined to the edges. (The figure is drawn from a fairly well 

 preserved specimen, so that it is not likely to be much different in liie 

 living specimens). In the skeleton (Fig. 68) only small dilTeiences from 

 species a are lo be noticed; the body rods and the transverse rods are 

 more straight and the end rods have apparently only one small process 

 on each side. 



') H. 1. udwig. Jugendfoniu'ii von Ophiureii. Silz.ber. kgl. Preiiss. .\kail. d. Wiss. 

 UtTliii. 18!)<). p. 212. 



