THE RECKNT CRINOIDS OF AUSTRALIA — CLARK. 775 



Diff'erential Characters. — Cyllometra studeri is most closely 

 related to C. inforniis, which was dredged by the " Challenger " 

 among the Philippine Islands. It differs from that species most 

 obviously in its smooth pinnules, the lower and middle pinnules 

 in the latter having slightly overlapping and spinous ends to the 

 segments, and in the much greater length and slenderness of Pg 

 which is twice as long as Pg with eighteen segments most of 

 which are elongated, instead of only slightly when at all longer 

 than P3, with twelve segments, most of which are squarish. Both 

 species are readily distinguished from all the others of the genus 

 by the small number of cirrus segments. 



Australian Record — The type and only known specimen of 

 this species was collected by the naturalists of the German steamer 

 " Gazelle," at Turtle Bay Anchorage, Dirk Hartog Island, in 7 

 fathoms. 



Genus OLIGOMETRA, ^. //. Clark. 



Oligometra, 1908, A. H. Clark, Proc. Biol. Soc. Washington, vol. 

 21, p. 216 (Antrdon serripinna, P. H. Carpenter, 1881). 



Differential Characters. — The species of Oligometra are all 

 small ; they possess ten arms as in Decametra, but the first inner 

 pinnule (P«) is always present. The cirri are short, rarely with 

 more than twenty-five segments almost all of which are about as 

 long as broad and bear across the middle of the dorsal side a ser- 

 rate transverse ridge which appears as a small median spine in 

 lateral view ; the opposing spine is small, but prominent, median 

 and erect. One or more of the lower pinnules (usually Pj^ orPg) 

 is enlarged, and its segments may bear lateral processes. 



Range. — Oligometra occurs from South-eastern Africa to Ceylon 

 and northern and eastern Australia, the Tonga Islands and the 

 Philippines, and northward to Japan. 



OLIGOMETRA CARPENTERI {Bell). 



Antedon carpenteri, 1884, Bell, Rep. Zool. Colh H.M.S. "Alert," 



p. 157, pi. X., figs. Aa-c (Port Curtis). 

 Antedon milberti (part), 1894, Bell, Proc. Zool. Soc, 1894, p. 394 



{North-western Australia). 

 Antedon serripinna, 1894, Bell, loc. cit. 

 Oligometra carpenteri, 1908, A. H, Clark, Proc. Biol. Soc. 



Washington, vol. 21, p. 126. 

 Differential Characters. — This is a slender and delicate little 

 species, much resembling 0. serripinna; P^ is small, and Pg 

 greatly enlarged with long lateral processes on the segments. 



