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



members of which have either the second or the third pinnule (or both) distinctly larger 

 than the first one. In a few species like Antedon elongata and Ante don jiagellata the 

 third pinnule is the largest, as in the ten-armed Antedon variipinna (PI. XXXVI. 

 figs. 1, 4-6). In others, again, like Antedon articulator and Antedon regalis, the second 

 and thud pinnules are of about equal size, as in the ten-armed Antedon parvicirra 

 (PI. XXXVI. fig. 8). But in Antedon palmata, and in the majority of the species com- 

 posing the group, the second pinnule is considerably larger than both the first and the third 

 (PI. XLVIII. fig. 2 ; PI. XLIX. fig. 4), just as in Antedon pinniformis of the Milberti- 

 group. The parallel between the two groups may be continued yet further; for the singular 

 Antedon informis, which is without a pinnule on the third brachial (PI. XXXIII. fig. 3) 

 has two representatives in the Palmata-grou]), viz., Antedon disciformis (PI. XXXIX. 

 fig. 4), and Antedon manca (PI. XLIV. figs. 2, 3). The first of these has no axillary 

 beyond the distichals, but palmars are present in Antedon manca as in most species of 

 the group ; and there are usually six arms to each ray, of which only the two outermost 

 usually have pinnules on the second brachials. 



Besides Antedon disciformis, Antedon clemens and Antedon marginata (PI. XXXIX. 

 fig. 5 ; PL XL. fig. 1) are the only members of the group which have but one post- 

 radial axillary. Some forms, like Antedon articulata, Antedon palmata, and Antedon 

 conjungens (PI. XLV. fig. 1), always have two and occasionally three; while we are not 

 yet acquainted with examples of Antedon Jiagellata, Antedon gyges, and Antedon 

 occulta (PL XLVIII. fig. 1 ; PL XLIX. fig. 3) in which a post-palmar axillary does not 

 occur on one or more of the rays. I have no doubt, however, that simpler forms of 

 these species will eventually be found, and I have, therefore, made no use of the presence 

 or absence of a post-palmar axillary for the purpose of classification. 



With the exception of the three species (Antedon occidta, Antedon similis, and 

 Antedon tubercidata), which were dredged by the Challenger at one of the three 

 Stations 174b, c, or D (255, 610 or 210 fathoms), all the members of the Palmata- 

 group belong to the littoral fauna ; and they are exclusively limited to the Western 

 Pacific and the Indian Ocean. They are extremely abuudant between the Friendly 

 Islands on the east, and the Mergui Archipelago on the west, ranging northwards as far 

 as Southern Japan, but not extending to the south beyond the tropic of Capricorn. 

 Isolated species occur at the Sandwich Islands on the east and also at Ceylon and 

 Rodriguez on the west ; while Antedon palmata, the type of the group, is common at 

 Aden and in the Red Sea. This is the furthest western limit of the group, which is 

 altogether unrepresented in the Atlantic ; for all the bidistichate species of Antedon 

 from the Caribbean Sea have plated ambulacra, and therefore belong to the Spinifera- 

 group. 



The mutual relations of the various species composing the Palmata-grou-p are shown 

 in the following key: — 



