3U THE VOYAGE OF H.M.S. CHALLENGER. 



Mouth apparently radial ; disk naked. 



Colour in spirit, — light brownish- white. 



Disk G'5 mm.; spread 8 cm. 



Locality. — Samboangan ; 10 fathoms. Two specimens. 



Other Localities. — Australia (Peron and Lesueur). 



Remarks. — I believe these two specimens to be identical with the form to which 

 Lamarck gave the name Comatula rotalaria. According to Midler's diagnosis, 1 "Die 

 Radien bestehen aus 2 durch Syzygie verbundenen Gliedern. Auf diese folgen 

 uumittelbar wieder d ia, die wieder mit Syzygie versehen sind. Dann folgt nur 

 noch selten weitere Veiasteluug, also 20 Arme die Grundzahl." 



When I visited the Paris Museum in 1876 I found that it contained no specimen 

 bearing Lamarck's name, but that a form which had been brought from Australia by 

 Peron and Lesueur, and appeared to be the original type of Lamarck's species as redefined 

 by Muller, was labelled Comatula brevicirra, Troschel. 



The first radials are not very distinct, but they are undoubtedly present, and there is 

 no syzygy either between the two outer radials, or between the two distichal joints, as 

 described by Muller according to Troschel's diagnosis ; while the two palmar series which 

 are present each consist of three joints, the axillary with a syzygy. 



The two individuals obtained by the Challenger at Samboangan present the same 

 characters and also retain their cirri, which are lost in the Lamarckian type. As i3 

 sometimes the case in Actinometra pectinata, there are five pairs which are placed 

 interradially or nearly so (PI. LIX. fig. 2), and have only ten or twelve joints. Tri- 

 distichate se.ies occur abnormally in both examples, whde there are sometimes only 

 two palmars instead of three. 



The only type which resembles Actinometra rotalaria in the characters of its arm- 

 divisions is Actinometra valida (PI. LIX. fig. 3), which is altogether a larger form with 

 more arms and more cirri. Actinometra simplex is also bidistichate but has no palmars, 

 while the cirri are longer and more numerous (PL LIX. fig. 1). 



4. Actinometra valida, n. sp. (PI. LIX. fig. 3). 

 Specific formula — a. 2. 3. 3.—. 



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

 fifteen cirri, which have some fifteen tolerably uniform joints ; the terminal ones laterally 

 compressed with a faint dorsal spine. 



First radials just visible ; the second closely united laterally. The rays are wide, and 

 1 Abhandl. d. k. Akad. d. Wus. Berlin, Jahrg. 1847 [1849], p. 256. 



