REPORT ON THE ORINOIDEA. 313 



Remarks. — This is a curious little species, which differs altogether from Actinometra 

 elongata in the shortness of the arm-joints and in the non-appearance of the first radials 

 externally. It has many resemblances to Actinometra parvicirra, but is separated from 

 that type by its smaller number of distichal joints. It presents, however, the same 

 difference in the lengths of the anterior and posterior arms as occurs both in Actinometra 

 parvicirra and in Actinometra elongata; but some of the hinder arms are non-tenta- 

 euliferous, which is not the case in Actinometra elongata. Their distal pinnules may 

 have dark spots in the centre of the dorsal surface which appear to be rudimentary forms 

 of the "ovoid bodies" that occur in Actinometra parvicirra and Actinometra elongata. 

 They are comparatively small and insignificant, and do not occur on the pinnules of the 

 anterior arms. 



3. Actinometra rotalaria, Lamarck, sp. (PI. LIX. fig. 2). 



Specific fo rmula — a. 2.3.—. 



1816. Comatula rotalaria, Lamarck, Histoire Naturelle des Animaux sans Vertebres, Paris, 



1816, t. ii. p. 534. 

 1834. Comatula rotularia, de Blainville, Manuel d'Actinologie, Paris, 1834, p. 249. 

 1841. Aledo rotalaria, Miiller, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 1841, p. 184. 

 1843. Aledo rotalaria, Miiller, Archiv f. Naturgesch., 1843, Jalirg. ix. Bd. i. p. 136. 

 1849. Comatula (Actinometra) rotalaria, Miiller, Abhandl. d. k. Akad. d. Wiss. Berlin, Jalirg. 



1847 [1849], p. 256. 

 1862. Comatula rotalaria, Dujardin and Hupe, Hist. Nat. des Zoophytes, lichinodermes, Paris, 



1862, p. 204. 

 1879. Actinometra rotalaria, P. H. Carpenter, Trans. Linn. Soc. Lond. (Zool.), ser. 2, 1879, 



vol. ii. p. 27. 

 1882. Actinometra rotalaria, Bell, Proc. Zool. Soc. Lond., 1882, p. 535. 

 1882. Actinometra rotalaria, P. H. Carpenter, Ibid., p. 747. 



Centro-dorsal a small, thin disk, bearing about ten cirri, of ten or twelve joints, none 

 (if which are much longer than wide. 



First radials just visible ; the second closely united laterally. Two distichals, the 

 second axillary without a syzygy, and three palmars, the third axillary with a syzygy, 

 Twenty to thirty arms, of about eighty subtriangular and overlapping joints ; some of 

 the hinder arms may be non-tentaculiferous. 



Syzygies in the third, tenth, and fourteenth segments, with others at intervals of 

 three or four joints. 



The second palmar, when present, has a moderately long pinnule with rather stout 

 lower joints. The next pinnule is nearly as long, but that of the third brachial is much 

 smaller ; and the next pair are also small, after which the pinnules increase considerably 

 in both length and stoutness. The terminal comb is rather small, and does not extend 

 beyond the sixth brachial. 



(zool. CHALL. EXP. PART LX. — 1888.) Ooo 40 



