The Echinoderm Fauna of South Africa. 313 



Disk without, or with a fugaceous coat of granules; arm-spines rarely 

 more than 3, uppermost often decidedly longest (numerous and subequal 

 in Ophiomusium lymani). 



Arms inserted laterally to disk; arm-spines 3 or rarely more 



Ophiolepididae, p. 353. 



Arms inserted ventrally to disk; ventral arm-plates small, covering 

 only a narrow median area on lower surface of arm ; arm-spines 2 



Ophioleucidae, p. 365. 



Statements made in the above key are not intended to apply to each family 

 as a whole but only to its South African representatives. 



OPHIOMYXIDAE. 



This family seems to have but two representatives in South Africa, 

 each representing a wide-spread genus. Each occurs in the PIETER 

 FAURE collection but each has been recorded before at least once. 

 They may be distinguished from each other as follows: 



Key to the South African Species of Ophiormjxidae. 



Second (outer) oral tentacle-pore small, opening within the mouth slit; oral papillae 

 flat with wide somewhat serrate tips, the distalmost smallest Ophiomyxa vivipara. 

 Second oral tentacle-pore large, opening on oral surface of mouth plate; oral 

 papillae spiniform, the 3 distal ones conspicuously longest and largest 



Ophioscolex dentatus. 



OPHIOMYXA VIVIPARA. 



Studer, 1876. Monatsb. K.-Preus. Akad. wiss. Berlin, p. 462. 

 H. L. Clark, 1915, Mem. M. C. Z., vol. 25, pi. 2, figs. 1, 2. 



The specimens at hand agree very well with those taken by the 

 CHALLENGER on the Agulhas Bank, but they are not so closely 

 similar to specimens from the Strait of Magellan. The available 

 material is neither of sufficient quantity nor of suitable quality to 

 determine whether the South American and South African are actually 

 identical. The few specimens before me suggest that they are dis- 

 tinguishably different. The largest of the PIETER FAURE specimens 

 is about 20 mm. across the disk (dry) and has arms 80-90 mm. long. 

 It is of a nearly uniform pale reddish-brown, the disk somewhat 

 darker. 



Station 2528. Lion's Head, N. 63 E., 34 miles, 154 fms. Blk. spc. 

 5 specimens; adult. 



Station 13225. Cove Rock, N.W. 3 / 4 W., 13 miles, 80-130 fms. 

 Crl. and r. 1 specimen; adult. 



