312 THE VOYAGE OP H.M.S. CHALLENGER. 



the case. But the distal pinnules in at least five of the posterior arms are provided with 

 the curious ovoid bodies on their dorsal aspect which I have noticed in some forms of 

 Actinometra parvicirra. 1 In the latter type the pinnules which bear these bodies are 

 generally non-teutaculiferous ; but this is not the case in Actinometra elongata. 



The centro-dorsal of this form is very thin, with much reduced cirrus-sockets, and is 

 evidently in process of transformation into the P/iano^enia-condition shown on the same 

 plate (PI. LVII. figs. 1, 2). One of the arms has been broken at the syzygy in the third 

 brachial, and the new epiz)'gal is an axillary, as is so frequently the case. This fact may 

 possibly indicate that when pah ars are developed in this type, there are normally three 

 with a syzygy in the axillary, so that it would then be allied to Actinometra rotalaria 

 and Actinometra valida (PL LIX. figs. 2, 3). 



The terminal comb on the oral pinnules is rather a small one, but it may occur at 

 intervals to some way out on the arms. The disk is very large and prominent, without 

 any trace of calcareous deposits, and the radial position of the mouth is not very distinct 

 (PI. LVII. fig. 3). 



2. Actinometra simplex, n. sp. (PI. LIX. fig. 1). 

 Specific formula — a. 2.—. 



Description of an Individual. — Centro-dorsal a thin disk bearing about fifteen 

 marginal cirri with fourteen to seventeen segments, a few of which are longer than broad, 

 First radials concealed, and also portions of the second, which are partly united laterally. 

 Two distichals, the axillary without a syzygy. 



Eighteen arms ; the anterior with one hundred joints, as compared with forty-five in 

 the posterior arms, some of which are non-tentaculiferous. The joints are short, sub- 

 triangular, and slightly overlapping, becoming more elongated at the ends of the anterior 

 arms. A syzygy in the third brachial, and the next about the tenth brachial, with 

 others at intervals of two to four joints. 



The second brachial bears a pinnule about 7 mm. long, and the following pinnules 

 diminish to those on the fifth and sixth brachials, afterwards increasing again. The 

 terminal pinnules of the anterior arms are very long and slender, those of the posterior 

 arms being shorter and stouter. The first four pinnules on each side have a small 

 terminal comb, which is found at intervals till near the ends of the arms. 



Mouth interrarlial; a few calcareous granules on the disk. 



Colour in spirit, — the skeleton a dull green, and the ventral perisome deep brown. 



Disk 8 mm.; spread 9 cm. 



Locality. — The Admiralty Islands; 16 to 25 fathoms. One specimen. 



1 Trans. Linn. Hoc. Lond. (Zool.), ser. 2, 1879, vol. ii. p. 40, pL ii. fig- 6, o.b. 



