14 ^ Mindeskrift for J. Steenstrup. X. 



are present on the young, growing arm joints, but gradually become 

 absorbed, and are completely lacking on the grown arm-joints. 



The vertebræ of Ophioteresis are not more primitive than those of 

 other Ophiurids. The division of the simple-armed Ophiurids into 

 Zygophiuræ and Streptophiuræ cannot be maintained, the difference 

 said to exist between them with regard to the articulating surfaces 

 of the vertebræ not existing in reality, 



Ophioteresis belongs to the Ophiothrichidæ, being very nearly rel- 

 ated to Ophiothela. The sipecie s Ophiothela tigris Lym. must also be referred 

 to the genus Ophioteresis, the two species tigris Lym. and elegans Bell 

 being probably identicaP). 



The so-cailed "pedicellariæ" of Trichaster and other Astrophytids 

 are only the elongated side arm-plates carrying the hook-shaped arm- 

 spines; they have nothing to do with pedicellariæ, these organs being 

 entirely unknown in Ophiuroids. 



I shall here add the description of the new species af Ophiothela mentioned 

 above (p. 5), naming it 



Ophiothela vineula n. sp. 

 (PI. I. Figs, 11—13). 



Diameter of disk in the largest specimens 5 mm., length of arms ca. 20 mm. 

 Arms five. The disk is covered by more or less rounded grains of different sizes, 

 only the large, triangular radial shields being distinct, though some scattered grains 

 are found on them also. In the middle of the disk the grains are generally larger 

 and somewhat pointed ; also those in the narrow interradial line separating each 

 two adjoining pairs of radial shields are larger, and the outer ones are even some- 

 times developed into rather large, coarse, pointed spines. Interbrachial spaces 

 below covered by naked skin with a few scattered grains ; the naked part begins 

 at the outer end of the radial shields and may be observed from the dorsal side, 

 when the interbrachial spaces are somewhat swollen on account of the genital organs. 

 At the sides of the arms there is, just below the outer end of the radial shields a 

 small group of grains. The oral shields are small, rounded, somewhat irregular in 

 shape ; the side mouth shields are short, but broad. The exact shape of these piates 

 as well as of the arm-plates cannot be made out by simply drying the specimens, as the 

 thick skin which covers the whole underside obscures their limits. On dissolving the 

 skin (with Eau de Javelle) the shape of the piates is made clear (textfigure 3). 



') See Additional Note, p. 16. 



