208 
the articular surfaces are rather peculiar, but a detailed description 
thereof seems to me superfluous; I may refer to the figures 6—9 
ob PETE 
The affinities of this curious little Ophiurid are rather difficult 
to make out, the more so as the classification of the Ophiurids is; 
upon the whole, far from being satisfactorily settled as yet. The 
covering of the disk recalls such forms as Ophiomastus and Ophio- 
typa, but much weight can scarcely be laid upon this structure, 
as a similar plating is found quite generally among young Ophiurids. , 
The armature of the mouth is similar in Ophiotypa, which appears 
also to lack the bursæ. On the other hand Opkiotypa differs: from 
Microphiura in having no radial shields,. besides in the presence 
of dorsal arm-plates, of large tentacle scales in the whole length 
of the arm, and in having only one arm-spine, the joints being non- 
constricted. The arm-structure of Microphiura, on the other hand, 
recalls the genus Ophiotrochus, which has, however, small dorsal 
plates; this genus has also grains on the disk and a somewhat 
similar armature of the mouth, but otherwise it differs from Micro- 
phiura in several important characters (presence of bursæ, large 
radial shields etc.). To Ophiohelus, which it recalls in the curious 
structure of the vertebræ, Microphiura has scarcely any nearer 
relation. Upon the whole, Microphiura does not appear to be very 
nearly related to any Ophiurid hitherto made known. 
The genus Microphiura may be thus diagnosed: Disk very 
small, covered with few large plates, the "primaries” being very 
conspicuous, while the radial shields are very small. Buccal shields 
nearly vertically placed. Å single, large mouth-papilla to each side 
of mouth-angle; one tooth. No bursæ. Ventral plates well developed, 
dorsal arm-plates wanting. Spines smooth. Pores continuing to 
the end of the arm, the papillæ like the arm-spines, except that 
on the first pore. Vertebræ only partly coalesced. The disk is 
very easily thrown off through autotomy. 
