THE OPHIURIDiE. 



143 



# 



than in Lyman's specimens^ only three times the diameter of the disk. 

 Lyman gives the length of the arms as five times the diameter of the disk. 



Lyman has referred this species to Amphmra^ but in this he is evidently 

 wrong. It must be emphasized that one of the most essential features of 

 -Amplmira is that there are two large mouth papillae at the apex of jaw^ below 

 the teeth. Ophiurans which have not that character cannot be named Am- 

 flimra. (At the same time it cannot be said that all Ophiurans with that 

 character belong to the genus Amphiura.) Especially the genus OjMactis 

 can only be distinctly separated from Amphiiira through that feature. 02)Id- 

 actis has never two mouth papilte at the apex,^ but only one small one 

 (which may also be considered as the lowest tooth). Some more of Lyman's 

 species o^ Amphkira thus evidently are also to be transferred to OjMadis, — 

 A. canescens Lyra, and A. patula Lym. Further, one of the species described 

 by KoEnLEK (67), Amp)hiura partita^ evidently should also be transferred to 

 Op)]iiactis y being closely related to 0. diipVicata^ as it has the same remark- 

 able feature of the divided first ventral plate. Curiously enough another of 

 the species described by Koeiiler (67), and referred to Opldactisy namely, 

 0. Lorioli^ evidently is an Ainp)hmra. 







26. Amphiura serpentina n. sp. 



Plate VIII. Figs. 1-8. Plate IX. Figs. l-ti. 



Diameter of disk, 9 mm. ; width of arm close to disk, without spines, 

 1.5 mm. ; length of arms, 7-8 times the diameter of the disk. Two mouth 

 papillae on each side of the mouth angle, the outer one large, irregular^ 

 often with two lobes, sometimes wholly divided in two. Mouth shield a 

 little longer than wide, with inner edge strongly rounded ; its Outer part is 

 restricted, stalk-like, outer edge rounded. Side mouth shields separated or 

 scarcely meeting within, much wider without than within. , 



First ventral plate small, six-sided. Those beyond all in mutual contact, 

 with inner end truncated, outer edge straight or slightly concave j outer 

 corners much rounded; outer laterals almost straight, the inner re-enter- 

 ingly curved. They are equally broad and long; at the inner end they 

 have a feeble keel. Side arm-plates with a well marked spine ridge ; on 

 the inner part of the arm there is a naked space outside each tentacle pore, 



* In 0. diipHcata, however^ tliere are sometimes two mouth papillae at tlie apex, but never on more tlian 

 one or two of the jaws. 



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