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



amongst which was Antedon granulifera with " three brachials between primary and 

 secondary axials, two between secondary and tertiary." The first part of this statement 

 clearly indicates that the type has three distichals, of which the axillary is a syzygial or 

 double joint. But it was impossible to tell from Pourtales' description whether the two 

 palmare are articulated or united by syzygy, though the latter condition seemed probable 

 from his further note that " sometimes there are syzygia in the first and second joints of 

 the arms." When the "Blake" collection came into my hands I found not only that 

 Antedon granulifera has the same grouping of the arms as Antedon distincta, but also 

 that it has an ambulacral skeleton and the rays flattened laterally, two characters of 

 which no hint was given in Pourtales' description. In fact, these two species, though so 

 widely separated geographically, are in reality very closely allied, the chief point of 

 difference between them being the greater size of the lower pinnules in Antedon 

 granulifera. 



Antedon distincta differs from Antedon angusticalyx and Antedon miequalis in the 

 long interval between the first and second syzygies of the arms, and also in the 

 separation of the distichal axillaries of adjacent rays by the pinnules on the preceding- 

 joints, which are attached nearer to the dorsal surface than usual. This is less marked 

 in Antedon granulifera, though it agrees with Antedon distincta in the long syzygial 

 interval. On the other hand, the joints of the genital pinnules of Antedon distincta are 

 more uniformly expanded than in Antedon granulifera, which rather resembles Antedon 

 angusticalyx and Antedon inwqualis in this respect. But in all four species alike the 

 outer side of each pinnule-joint is more expanded than the inner one, just as in Antedon 

 hasicurva and Antedon incisa (PI. XXI. fig. 2), while in the tridistichate variety of 

 Antedon multispina the large joints of the pinnules are broadly V-shaped and similarly 

 expanded on both sides. 



Antedon granulifera seems to be fairly abundant in the Caribbean Sea; but it 

 exhibits a good deal of variation in its characters, which will be fully discussed in the 

 report on the " Blake " Comatulse. 



4. Antedon midtispina, n. sp. (PL XIII. figs. 1-3 ; PI. XIV. figs. 5-7 ; PL L. 

 figs. 3-6 ; PL LXIX. figs. 1-4). 



Specif c formula — A.f — J. y. 



Localities.— Station 135g, October 18, 1873; off Tristan da Cunha; lat. 37° 10'50"S., 

 long. 12° 18' 30" W.; 550 fathoms ; hard ground. One mutdated specimen. 



Station 344, April 3, 1876 ; near Ascension; lat. 7° 54' 20" S., long. 14° 28' 20" W.; 

 420 fathoms ; volcanic sand. Four broken individuals and three Pentacrinoids. 



