198 THE VOYAGE OF H.M.S. CHALLENGER. 



and also the first two brachials have the margins of the dorsal surface flattened, with 

 straight lateral edges, and in some arms this character also extends on to the hypozygal 

 of the third brachial, but the wall-sidedness is always much less distinct than in the 

 Basicurva-grou-p, and in some examples is scarcely visible at all ; while there are no 

 indications of the flattening of the sides of the first pinnule which is so characteristic of 

 Antedon basicurva, Antedon valida, and their allies (see woodcut fig. 3, on p. 122). 

 Furthermore Antedon milberti has unplated ambulacra, and in all other respects it is 

 closely allied to Antedon anceps, Antedon serripinna, and the other species which I have 

 placed with it in the same group. At the same time the indications in this distinctly 

 littoral type of a peculiarity which is especially characteristic of Comatulae from the 

 continental and abyssal regions is a point of considerable interest. 



Some of the examples of this species which were dredged at Mergui were infested 

 by a species of Myzostoma which Professor von Graff has been unable to determine 

 satisfactorily, owing to its state of preservation. 



2. Antedon anceps, n. sp. (PI. XXXV. figs. 1-3). 

 Specific formula — A.(3).y. 



Locality.— -Station 212, January 30, 1875; lat. 6° 54' N., long. 122° 18' E.; 10 

 fathoms ; sand. 



Remarks. — Of the three individuals of this species which were dredged by the 

 Challenger, one has ten arms, while the other two have three and four distichal series 

 respectively. The type will therefore be described together with the remaining members 

 of the tridistichate group. But a few words may be said here about its ten-armed 

 variety. It has a considerable superficial resemblance to the less tubercular forms of 

 Antedon milberti, with which it agrees in the characters of its arm-joints ; but the third 

 outer pinnule (on 6 br.) is larger than the second (on 4 br.), as seen in PI. XXXV. 

 fig. 2, which represents the pinnules on the inner side of the arm, i.e., on the third and 

 following brachials. The cirri, too, have smooth joints, and so are very different from 

 the spiny cirri of Antedon milberti (PL XXXV. figs. 3, 4). 



3. Antedon variipinna^ Carpenter (PL XXXVI. figs. 1-6). 

 Specific formxda — A.[3.(2)].y. 



Locality. — Arrou Islands. 



Remarks. — Most individuals of this species are distinctly tridistichate, but the two 

 from the Arrou Islands seem to owe this character to a regeneration after fracture at 



1 A revised diagnosis of this species, together with its synonymy, will be fonnd on p. 256. 



