A MONOGRAPH OF THE EXISTING CRINOIDS 53 



broadened to protect the gonads; P] is the longest and stoutest pinnule, with 12 seg- 

 ments; the short and stout cirri have 14-17 (usually 15) segments, all of which except 

 the penultimate hear a transverse ridge. 



This genus is closely related to Analcidometra from which it is easily distinguished 

 by the occurrence of a transverse ridge on all the cirrus segments preceding the penul- 

 timate. 



Geographical range. Coast of southeastern Australia from off Wollongoiig, 

 New South Wales, southward to Bass Strait, between Australia and Tasmania. 



Bathymetrical range. From 102 (?100) to 128 meters. 



History. The single species of this genus was described under the name of Oli- 

 gometra thetidis by Dr. Hubert Lyman Clark in 1909. In 1915 I transferred it to the 

 genus Oligometrides. In 1916 I established the genus Austrometra with Oligometra 

 thetidis as the genotype. This new genus was said to be most closely related to 

 Analcidometra, with which it agrees in possessing expanded genital pinnules, a char- 

 acter not known to occur elsewhere in the family. Both Austrometra and Analcido- 

 metra were saidfto beTelatedJto'OKf/OTnefndes'more colsely than to any other type In 

 1918 I included Austrometra in the key to the genera of the family Colobometridae 

 in my report on the unstalked crinoids of the Siboga expedition, and in 1934 Dr. 

 Torsten Gisl^n discussed the articulations in the IBr series, the expansion of the 

 genital pinnules, and the pinnule articulations hi this genus. 



AUSTROMETRA THETIDIS (H. L. Clark) 



[See vol. 1, pt. l.fig. 317 (cirrus tip), p. 273; fig. 354 (cirrus), p. 293; pt. 2, fig. 324 (proximal pinnules) , 

 p. 227; figs. 340, 341 (proximal pinnules), p. 229; figs. 498-501 (details of pinnules), p. 273.] 



Oligometra thetidis H. L. CLARK, Mem. Australian Mus., vol. 4, part 11, 1909, p. 522 (description) 

 comparisons; off Wollongong, 55-56 fms.), pi. 47, figs. 1-3. A. H. CLARK, Die Fauna Siidwest- 

 Australiens. vol. 3, Lief 13, 1911, p. 441 (Australian tropical species occurring south to Wollon- 

 gong) ; Mem. Australian Mus., vol. 4, 1911, p. 722 (confined to south Australia), p. 725 (related 

 to O. adeonae), p. 735 (in key), p. 777 (original reference; detailed description; characters; 

 locality; resemblance to Analcidometra caribbea [armata]) ; Records of the Indian Mus., vol. 7, pt. 

 3, No. 26, 1912, p. 267 (a species related to this and to 0. adeonae discovered in the Andaman 

 Islands) ; Crinoids of the Indian Ocean, 1912, p. 9 (confined to south Australia), p. 175 (synony- 

 my; locality).- H. L. CLARK, Biol. Results Fishing Exper. F. I. S. Endeavour, 1909-14, vol. 4, 

 pt. 1, 1916, p. 22 (eastern slope, Bass Strait, 2 specimens). A. H. CLARK, Unstalked crinoids of 

 the Sifcoya-Exped., 1918, p. Ill, footnote 1 (type of Austrometra'). Port, Australian Mus. 

 Mag., vol. 8, No. 12, 1945, p. 407 (but not fig. on p. 406= Metacrinus sp.). 



Oligometrides thetidis A. H. CLARK, Die Crinoiden der Antarktis, 1915, p. 167 (range) ; Internat. Rev. 

 gesamt. Hydrobiol. und Hydrogr., 1915, pp. 225 and following (detailed account of the distri- 

 bution in Australia). 



Austromelra thetidis A. H. CLARK, Journ. Washington Acad. Sci., vol. 6, No. 5, 1916, p. 116 (range); 

 Proc. Biol. Soc. Washington, vol. 31, 1918, p. 41 (listed from Tasmania). GISLN, Zool. 

 Bidrag Uppsala, vol. 9, 1924, p. 79 (syzygies) ; fig. 165, p. 98 (pinnule articulation). H. L. 

 CLARK, Mem. Mus. Comp. Zool., vol. 55, 1938, p. 40 (southwest of Gabo Island, New South 

 Wales; 70 fathoms; notes). H. L. CLARK, Echinoderm fauna of Australia, 1946, p. 50 (localities). 



Description. The centrodorsal is low hemispherical with a rather large bare polar 

 area. The cirrus sockets are arranged in 2 irregular closely crowded rows. 



The cirri are XV-XX, 15 (rarely 14, 16, or 17), short and stout. The first seg- 

 ment is very short, the second is somewhat longer, the third is still longer, and the 

 fourth and following are about as long as broad. The fourth and following segments 



