AA MARINE BIOLOGY OF THE SUDANESE RED SEA. 
Reports on the Marine Brotocy of the SuDANESE Rep Sea.—VII. The 
CrINoIDEA. By Hersert C. Cuapwick, A.L.S., Curator of the 
Port Erin Biological Station. (Communicated by Prof. W. A. HeRDMAN, 
D.Sc. F.B.S., P.L.S.) 
[Read 5th December, 1907. ] 
TuE collection of Crinoidea made by Mr. Cyril Crossland on the Sudan coast, 
and submitted to me for examination, contains six species, only two of which 
appear to have been previously recorded from the Red Sea. It is worthy of note 
that the genus Actinometra is not represented in the collection. In describing 
the position of the syzygies in the arms I have adopted, with some hesitation, 
the view so strongly urged by Bather in his paper entitled “ The Term Syzygy 
in the Description of Crinoids” (Zoologischer Anzeiger, No. 495, 1896), to 
the effect that the epizygal and hypozygal elements which form what is 
commonly known as a syzygial pair should be regarded as morphologically 
equivalent to the ordinary brachial ossicles which are united by muscular 
bands, and not as forming together one such ossicle. I may perhaps be 
allowed to point out one objection to Bather’s view which appears to me to 
have some weight. On page 117 of Vol. iil. of Lankester’s ‘ Treatise on 
Zoology ’ a syzygy is described as “an immovable sutural union between two 
brachials of a pinnulate arm, accompanied with loss of the pinnule on the 
hypozygal.” Now, if it be true that in the past history of the Crinoidea the 
hypozygal was once pinnulate, it is remarkable that the pinnules of the 
epizygals are invariably on that side of the arm from which the pinnule has 
been lost. Take, for example, the great majority of the family Antedonide. 
The first pinnule is borne by the second brachial on the outer side of the 
armlet, and the second pinnule by the epizygal of the first syzygial pair (fourth 
brachial of Bather) on the inner side of the armlet. Butif the hypozygal has 
lost the pinnule which, it must be assumed, was on the inner side of the arm, 
that of the epizygal (fourth brachial) is on the wrong side, for it also is on 
the inner side. 
CRINOIDEA. 
ANTEDONIDK. 
ANTEDON SERRIPINNA, Carpenter. 
Several specimens of this species were dredged from a muddy bottom ata 
depth of 10 fathoms in Suez Bay. When living they were of a purplish- 
black colour, the arms of one specimen being regularly striped with yellow. 
The cirri consist of twenty-three ossicles, of which all, from the fifth 
onwards, have a transverse dorsal ridge. As in the specimens of this species 
collected by Prof. Herdman off the coast of Ceylon, the ridge is near the 
distal end in the first few ossicles and becomes median in the later ones. In 
