152 



of the posterolateral arms are coiitiiniing across the body, below the devel- 

 opiiii* Ophiurid. At the anterior end there is another transverse l)and, ap- 

 parently derived direelly from the preoral band. Thus a remarkable rear- 

 rangement of the vibratile bands takes place in this form, something corre- 

 sponding to what lakes place in the transformation of the Auricularia into 

 the pupa-stage (Cf. p. 125). A similar case was observed in Ophinpliileus 

 pusHlus, species b (PI. XXIX. l"ig.;>) and (). iindulnliis, species a (PI. XXIV, 

 iMg. .i). 



Species b. (PI. XXVII, Fig. 2). This species differs so conspicuously 

 from species a as regards its shape that it may seem doubtful, whether it 



Fig. 80. Skeleton of Ophiopliiteiis formosus, species b. -'"/i- 



really belongs to the same type. The inner arms are one and a half to two 

 times, the posterolateral ones more than four times the body length. The 

 arms are narrow, rounded, not broad and flattened as in species a. On 

 the other hand the skeleton (Fig. 80) so closely resembles that of species 

 a that only very small difTerences can be pointed out, the main thing 

 being that the transverse rods are somewhat more robust, the inilentations 

 at the ends being less deep. Perhaps the shape of the meshes of the body 

 skeleton will prove a little diflerent. In species a the meshes are somewhat 

 narrower at the lower end, which does not appear to be the case in the 

 present species; but as there is only one specimen, and thai one even 

 showing a slight difTerence in the shape of the two sides of the body skele- 

 ton, this feature is not to be relied upon as a specific difTerence. The thorns 

 on the posterolateral rods are blunt and more distant than in species a. 

 (Fig. 82, B). 



One single specimen, fairly well preserved, from the Red Sea, 24° 43' N. 

 35^45' K. 10/XI. 1899. 



