178 



OPHIOMYXA FLACCIDA. 



Ophiomyxa flaccida Lutkex, (pi. ii. Fig. G; Figs, is, 19.) 



Ophiura flacc'ula Say. Joum. Phil. Acad., Y. p. 151. 182.5. 

 Op/iioiiii/xa carihuea LDtkex. Vidensk. Meddolelscr. INIareb, 1856. 

 Ophiomyxa Jiaccida L'utkex. Addit. ad Hist. Oph., p. 138. 



Special Marks. — Color, alive, lake-red or orange ; in alcohol, olive 

 green or bright green, sometimes mottled with lighter. Four to six 

 arm-spines. Arms four or five times as long as diameter of disk. 



Desci^lption of a Specimen. — Diameter of disk, 22"""" ; from outer 

 side of mouth-shield to outer corner of opposite mouth-slit, 10"""'; width 

 of arm without spines, 4.5°"°- ; length of arm, 102™"- ; distance from 

 outer side of mouth-shield to inner points of teeth, to that between 

 outer corners of mouth-slits, 4.2 : 4.6. Mouth-papilla?, four to each side 



of the angle of the jaw ; the outer one is, 

 J_2i -■'■;■- however, rudimentary, and has no saw-like 



edge ; the others are of about equal size, but 

 the two inner ones have their saw-like edge 

 more coarsely divided than the second one. 

 Teeth eight, closely resembling mouth-papil- 

 la3 ; the upper ones with the cutting edge 

 more rounded and nearly smooth. Mouth- 

 shields and side mouth-shields without dis- 

 tinct outline, except in dried specimens ; the 

 former are rounded diamond-shape ; length 

 to breadth about 2 : 1.7. Side mouth-shields 

 long triangular, nearly meeting within. Under 

 arm-plates, in dried specimens, are fiintly indicated by an oval outline, 

 with a notch in the outer side ; length to breadth about 1 : 1.5. Upper 

 arm-plates, in dried specimens, appear as transverse, elongated, oval 

 ridges, with sharp lateral corners. Skin of the disk somewhat wrinkled. 

 Arm-spines four, short, flattened, conical, covered nearly to the tip with 



skin ; their thorns numerous ; second joint, 

 one spine ; third joint, two spines ; fifth joint, 

 three spines ; ninth joint, four spines ; lengths 

 to that of the joint (twelfth joint), 1.3, 1.1, 

 1.1, 1.1 : 2. The under arm-spine, near the 

 tip of the arm, has four or five little hooks 

 along its edge. Genital slits short, reaching only one half or two thirds 

 the distance to the margin of the disk, furnished with a small lobe near 

 the mouth-shields. Color, in alcohol : above, dirty olive-green, with a 

 few irregular rings of yellowish towards ends of arms ; centre of disk 



Ophiomyxa flaccida. (Upper side ) 



Fig. 19. 



Opiiiomyxa flaccida. 

 Chewing Apparatus from below. 



