774 " THETIS " SCIENTIFIC RESULTS. 



pinnules, except Pj, are very long and greatly stiffened, with 

 long spines about the distal ends of each segment ; the outer 

 pinnules have spinous segments, and the brachials are bordered 

 distally with long spines. 



Specimens in the Australian Museum Collection. — Port Jackson 

 — A small arm fragment. Lord Howe Island — One specimen, 

 without cirri ; the very stiff lower pinnules reach a length of 23 

 mm. (P2)j the arms were probably about 120 mm. long ; there 

 were xviii. cirri arranged in one and a partial second irregular 

 marginal row ; the dorsal pole of the centrodorsal is deeply con- 

 cave ; the synarthrial tubercles are but slightly marked ; in the 

 proximal portion of the arms there is a faint low rounded median 

 carination ; Pj, which is not stiffened like the succeeding, is only 

 half as long as P„. 



Additional Australian Record. — Port Denison, Queensland., in 

 3-4 fathoms. 



Range. — Colobometra perspinosa is known from Port Jackson 

 and Port Denison, Australia, from Lord Howe Island, and from 

 the Island of Jobie in Geelvink Bay, New Guinea. 



Genus D E C A M E T R A, ^. //. Clark. 



Decamelra, 1910, A. H. Clark, Proc. U. S. Nat. Mus., vol. 40, 

 p. 31 (Decametra mobiusi, sp. nov.). 



Differential Characters. — The species of the genus Decametra 

 have ten ai'ms and lack the first inner pinnule (P«) like those of 

 Colobometra ; but only P^ is enlarged, and that is not greatly 

 different from the following pinnules ; its component segments 

 are not especially long, and their distal ends are but slightly 

 when at all prominent, and the pinnule is slender and flagellate 

 distally. The cirri are short, and are composed of subequal 

 segments (instead of long proximal and short distal segments as 

 in Colobometra), the outer beaiing a more or less denticulate 

 transverse ridge, or sometimes a pair of small tubercles. 



Range. — Decametra occurs from South-eastern Africa and 

 Mauritius to Ceylon and North-western Australia, Singapore, and 

 the Philippine Islands. 



DECAMETRA STUDERI {A. H. Clark). 



Oligometra studeri, 1909, A. H. Clark, Proc. Biol. Soc. Washing- 

 ton, vol. 22, p. 41 (Dirk Hartog Island, 7 fms.). 



Cyllometra studeri, 1909, A. H. Clark, torn, cit., p. 88. — Zool. 

 Anzeiger, vol. 34, p. 368. 



