A. H. CLARK : THE CRINOIDS OF THE INDIAN OCEAN. 151 



Antedon jmlcher LOtken, MS. — 1891. Hartlaub, Nova Acta Acad. German., 



vol. , No. 1, p. 73. 

 Dichrometra flagellata 1909. A. H. Claek, Proc. Biol. Soc. Washington, vol. 22 



p. 13. 



Habitat. — New Guinea ; Amboiiia ; Singapore ; Pulau Ubin, Singapore ; 

 Pelew Islands ; ? Madagascar ; ? Zanzibar. 



Remarks. — In the type of Alecto flagellata, preserved at Leyden, the dorsal 

 pole of the centrodorsal is concave ; the cirrus spines are very small tubercles ; 

 the cirrus segments number 24, 25, 28 and 30. 



There are thirty-nine arms, the extra IIIBr series being external. The divi- 

 sion series and first six or eight brachials are in close apposition and are sharply 

 flattened laterally. 



Pi is very small and short ; P.;, is large, over twice as long as P,, of the same 

 character as P-, in D. protectus ; the component segments are slightly longer than 

 broad; Pj is slightly longer and larger than P.^; P^ is about the size of P, ; P^^ is 

 somewhat smaller than P^; the following pinnules are small and weak. The en- 

 larged lower pinnules are strongly curved outward and backward ; they stand 

 out very prominently through their large size, the middle and outer pinnules 

 being especially short. The centrodorsal is rather large. The cirri number XL. 



The type of Alecto elongata, also at Leyden, has about twenty very long and 

 slender arms; the cirri are XXIV, 25; there are six IIBr series and four IIIBr 2 

 (external) series. The longest cirrus segments are about one third longer than 

 broad ; the ninth or tenth and following bear small but prominent dorsal spines 

 The synarthrial tubercles are sUghtly prominent, and the basal portion of the 

 arms is rugose as in Z). protectus. The rays and division series are not in lateral 

 contact, though they have tolerably straight sides. The IBr, are entirely united 

 laterally, but the axillaries are free. There are no lateral processes as seen in 

 Stephanometra. Pg has from twenty to twenty-two segments ; P, is small and 

 weak'; P.^ is nearly twice as long as P,, and P„ is still longer. P^ is nearly as 

 long and large as P,,, intermediate between Pj and P.., ; P^ is much shorter: the 

 following pinnules are small and weak. 



The proximal pinnules as a whole resemble those of D. flagellata, but are 

 slightly less stiffened and more flexible, and more flagellate distally — at any rate 

 than in large specimens of flagellata like the type. There is no essential difference 

 between the type specimens of flagellata and elongata that cannot be perfectly 

 well accounted for by the difference in size of the two animals, and the two 

 appear undoubtedly to represent the same species. 



DICHROMETRA BIMACULATA. 



Antedon himaculata 1881. P. H. Carpenter, Note« from the Leyden Museum, 

 vol. 3, p. 186. 



