MUSEUM OF COMPARATIVE ZOULOGY. 



221 



Xo. 10. — Ophiuridce and Astrophytidcc, Old and New. By 

 Theodore Lyman. 



Ophiopeza Peters. 



Ophiopeza fallax Pet. is well distinguished from 0. Yold'd Ltk., as I 

 satisfied myself by examination of the originals at Berlin and Copenhagen. 

 Two specimens of the same size differed as follows : 0. fallax: diameter of 

 disk !) mm . ; grains on disk, 2G in a mm. long ; eighteen mouth-papilla; to 

 each angle; eight nearly equal, crowded arm-spines. 0. Yold'd: diameter 

 of disk, 9 mm.; grains on disk, 13 in a mm. long; five spaced arm-spines, 

 the middle one longest. Ophiopeza does not differ from Pectinura Fbs., ex- 

 cept in having small supplementary mouth-shields, and O. fadax even has 

 such pieces as an occasional accident. 



Pectinura Forbes. 



Liitken (Addit. ad Hist. Oph., III. pp. 31 and 10. r >) correctly separated 

 from Ophiarachna Midi, and Tr. those species which had spines arranged 

 along the outer edge of the. side arm-plates, and placed them with Pectinura 

 (Forbes, Linn. -Trans., XIX. 143). The original P. vestita of Forbes is only 

 known by the figure (PI. XIII., Figs. 1 -7), which is apparently that of a 

 young animal. In Ophiarachna only two species arc left, O. inerassata, the 

 largest known Ophiuran, having four arm-spines, and pores between the 

 under arm-plates nearly to the tip of the arm ; and 0. affinis, with six arm- 

 spines and pores only between the first and second under arm-plates. With 

 Pectinura should he included Ophiopezella Ljn. and Ophiochaxma Grube, 

 which are only extreme forms of this genus. Its species may then be tabu- 

 lated as follows: — 



Xo pores between 

 under arm-plates. 



f Radial shields, granulated, 13-15 1 „ T 



arm-spines ) R *P mosa L >" m - 



Disk cnv- . 

 ere J, under | 

 its g r a n u - { 

 lation, with 

 coarse scales, 

 or swollen 

 plates. 



Radial shields naked : also some I 



other disk-plates; 9 arm-spines 



P. in/ernalis Ltk. 



f Arms cylindrical at their inser- I p ■ ttk . 



tion in the disk, winch is puffed. ) 



Pores hetwcn first 

 and second under - 

 [ arm-plates. 



Arms widened ) 10-11 arm-spines. P. mannornta Lym. 

 at their insertion I 

 in the disk, which f 

 is flat. J 5-6 arm-spines. P. stellata Lkt.* 



* By comparing the originals I found Crube's Ophiochasma a'hpersitm was the Ophiarachna 

 stellata of Ljungman. 



