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



Remarks. — This fine species is sufficiently distinguished by the great size of its cirri, 

 which are considerably longer than those of any other Antedon that I have seen with 

 the exception of Antedon valida (PI. XV. fig. 5). The appearance of the tertiary basals 

 and of all three radials on the exterior of the calyx, together with the small size of its 

 lower pinnules, separate it very clearly from the two species which come nearest to it in 

 the characters of the cirri, viz., Antedon valida and Antedon incerta (PI. XV. fig. 5 ; 

 PI. XVIII. fig. 4). Both of these show little or nothing of the first radials externally, 

 and have large and peculiarly modified lower pinnules. 



Antedon longicirra is one of the few species of the genus which appear to be 

 unprovided with sacculi. The careful examination of several pinnules (both decalcified 

 and otherwise) has altogether failed to reveal their presence except in one doubtful case; 

 though from my experience with Antedon valida it is not improbable that they may 

 occur on other pinnules which I have not examined. But there are no notches for their 

 reception in the imperfectly differentiated side plates. In fact the ambulacra of this 

 species are more like those of the Pentaerinidae than is the case in any Antedon I know. 

 For there are no definite side plates, the covering plates resting on a continuous limestone 

 band which ceases some little way from the end of the pinnule, so that the last few joints 

 have no ambulacral skeleton at all, as in so many Pentacriniche (see Part I. p. 55 ; pi. xv. 

 fig. 7). 



2. Antedon valida, n. sp. (PI. XV. figs. 5-8). 

 Specific formula — A. — . 



Centro-dorsal large and conical with the ventral angles produced, and bearing about 

 fifteen cirri. These may reach 80 mm. in length and consist of about sixty -five joints, 

 of which the seventh to the twelfth are considerably longer than wide. From the 

 twenty-fifth onwards the joints are short and wide, with a strong dorsal spine. 



The first radials just visible ; second and third strongly convex in the middle of their 

 line of junction. The borders of all three radials and of the lowest brachials are fringed 

 with strong spines. The axillaries and first brachials have straight edges and flattened 

 sides. Second brachial and hypozygal of the third flattened on the inner side only. 

 The junction line of the first two brachials somewhat tubercular. 



Ten arms, of triangular, slightly overlapping joints, the later ones somewhat 

 compressed laterally. Syzygies in the third and about the twelfth brachials, and others 

 at intervals of four to fifteen joints. 



The second brachials have large stout pinnules, the first eight joints of which have 

 broad and flattened outer sides. The third, fourth, and fifth joints have their inner 

 edges bent upwards and somewhat thickened, but in the next following joints these are 



