REPORT ON THE OPHIUROIDEA. 



347 



Fio- 



1. Ophiotholia sxipplicans, Lym., ^ 



3. 



4. 



5. Ophiohelus 2^Uticidus, Lym. 



6. 



7. 



8. 



10 



T • 



30 

 1 • 



PLATE XXVIII. 



The entire animal seen in profile, with its 

 arms and disk stretched upward and 

 its mouth angles turned downward, and 

 outward, and armed with their mouth 

 papillae like those of Opkiomyces. On 

 the outer arm joints are the small 

 parasol spines. 

 Mouth seen from below, showing the spike- 

 like teeth, the foliate, imbricated mouth 

 papillae, and the two sets of mouth 

 tentacles. 

 Ninth arm joint from below, showing the 

 side arm plates bearing ordinary spines 

 and within them a bunch of parasol 

 spines. From the large pores issue long 

 smooth tentacles, each protected by a 

 spine-like scale. On drying the specimen 

 there would appear along the central ridge 

 the juncture of the side arm plates. 

 A single parasol spine mounted on its 



mamelon. 

 From below, showing the long mouth ten- 

 tacles, and the absence of parasol spines 

 near the base of the arm. 

 From above. The extremely thin disk scales 

 are barely visible by a cross light. The 

 arm bones are in two parallel pieces. 

 Ninth, tenth, and eleventh arm joints stripped 

 of skin. On the ninth are three common 

 and one parasol spine. On the other two 

 joints are only the latter sort, arranged in 

 a double row. 

 A common arm spine treated with potash, 

 to show that it is composed of two parallel 

 spicules, like a disk spine of Ophiohelus 

 umbella. 

 A parasol spine, mounted on its mamelon, 

 and stripped of its skin bag. 



75 



i • 



10 



i • 



10 



i • 



20 



i • 



40 



1 • 



50 

 I • 



