228 BULLETIN 82, UNITED STATES NATIONAL MUSEUM VOLUME 1 



The 10 arms are from 55 to 65 mm. (usually GO mm.) in length, stout and rugged, 

 resembling those of small stout specimens of A. bifida bifida. 



PI is 12 mm. long, with 25 segments and relatively less stout than the same pinnule in 

 A. mediterranea. P 2 is 5 mm. long, with 16 segments. The production of the distal 

 ends of the segments of the proximal pinnules is marked. 



Notes on the specimens. In the larger example from Messina, Sicily, which has 

 the arms 65 mm. long, the cirri are not so strongly recurved in the distal half as in 

 those from Tangier; the outer cirrus segments are very slightly longer than the lateral 

 diameter, becoming about one third again as long as broad terminally; the dorsal 

 profile of the distal cirrus segments is slightly concave. In a second specimen from 

 Messina, with the arms 55 mm. long, the outer cirrus segments have a straight dorsal 

 profile. The others from Messina are small, and their cirri are more like those of 

 A. mediterranea, the outer segments having a somewhat concave dorsal profile. The 

 larger specimen from Ajaccio, Corsica, in which the arms are 45 mm. in length, re- 

 sembles the young individuals from Messina. 



[NOTE BY A.M.C.] In some specimens from the Azores P t measures up to 15 

 mm., with 30 to 35 segments while Pj with 12 to 21 segments is 4 to 7 mm. long. 



Abnormal specimen. An example from Tangier with the arms 60 mm. long and 

 the cirri XXX, 14-16, has 11 arms, the right posterior IBr axillary bearing on the 

 right (i.e., anterior) side a single axillary ossicle. 



Remarks [by A.M.C.j. Since Mr. A. H. Clark first compiled this typescript, the 

 status of moroccana has been questioned by several authorities, notably Koehler (1927), 

 who thought it only a variety of bifida, Tortonese (1955), who thought it a synonym 

 of bifida and Gislen (also 1955), who thought it, together with Antedon hupferi from 

 the Gulf of Guinea, a synonym of the West Atlantic duebeni. I do not find convincing 

 Gislen's evidence for the existence of only a single species of Antedon throughout 

 northwest and west Africa and I think he was premature in synonymizing moroccana 

 and hupferi with duebeni on the present inadequate material of the latter. Considering 

 the variability of bifida and probably of some of the other species of Antedon also, a 

 number of specimens from related localities are needed before the characters of any 

 one form can be appreciated. 



There are 18 specimens in the British Museum which I believe may be referred 

 to moroccana, 13 from the Azores, 3 from Goree in Senegal and 2 from Algiers, for the 

 last of which I am indebted to Professor Tortonese. The table given here includes 

 measurements of peripheral cirri of 15 of these, the arm width at the first syzygy being 

 included as a criterion of size since complete arms are rare. The largest specimen had an 

 arm length of about 80 mm. Comparable measurements of 40 specimens of bifida from 

 various parts of the British Isles are given also for comparison. The ratio used to 

 express distal expansion of the cirri dorsoventrally is taken from the median widths 

 of the fourth segments from each end of the cirrus and is less than that which would 

 be obtained by taking the maximum and minimum widths, owing to the tendency 

 of the distal segments to exhibit some degree of flaring. Such a ratio would be about 

 2:1 (as Mr. Clark gives for moroccana} as opposed to about 1.8:1 when the median 

 widths are used. The median length of the fourth segment from the tip is also given 

 for comparison with the width, appearing to be rarely much greater in moroccana but 

 varying from equal to the width to a third again as long in bifida, though this result 

 may be only due to the small sample of moroccana, for which much more data is needed 

 to supplement the figures given here. 



