A MONOGRAPH OF THE EXISTING CRINOIDS 433 



Siboga Exped., 1918, p. 140 (in key; range; key to the included species). GISLN, Nova Acta 

 Reg. Soc. Sci. Upsaliensis, ser. 4, vol. 5, No. 6, 1922, pp. 86, 100, 101; Zool. Bidrag Uppsala, 

 vol. 9, 1924, pp. 79, 85, 91, 231. SIE VERTS, Neues Jahrb. Min., Geol. und Pal., vol. 69, Beilage- 

 Band, Abt. B, 1932, pp. 151, 156. GiSLfor, Kungl. Fysiogr. Sallsk. Handl., new ser., vol. 45, 

 No. 11, 1934, pp. 18, 20. EKMAN, Tiergeographie des Meeres, 1935, p. 283. H. L. CLARK, 

 Echinoderm fauna of Australia, 1946, p. 57 (key to the included Australian species). 



Diagnosis. A genus of Asterometridae in which the arms are 10 to 16, though 

 seldom over 13, in number; the pinnules of the proximal third of the arm are much 

 shorter than those of the distal half and are composed of segments which, except 

 occasionally at the extreme tip, do not have overlapping and spinous distal ends; the 

 longer proximal cirrus segments as viewed laterally have approximately straight 

 ventral and dorsal borders, though these may diverge slightly distally; there is no 

 central constriction or production of the distal edge. 



. Geographical range. From the Goto Islands and Kagoshima Gulf, southwestern 

 Japan, and the Bonin Islands southward to the Kei Islands and the Sahul Bank 

 (south of western Timor), and westward to Bali. 



Bathymetrical range. From 73 (?72) to 256 meters. 



Thermal range. One record, 15.89 C. 



Remarks. The species of the genus Asterometra have a very characteristic appear- 

 ance, the small number of arms, compact proximal structure and very large cirri 

 distinguishing them at a glance. They are divided into two sections in one of which, 

 including only anthus, the division series and arm bases are smoothly convex dorsally, 

 while in the other, including mirifica, cristata, macropoda, and longicirra, they are 

 carinate. The species of the last section differ very little except in the extent and 

 degree of the proximal carination. 



History. The first known species of this genus was described under the name of 

 Antedon longicirra by Dr. P. H. Carpenter in 1888. This species was transferred to 

 the new genus Ptilometra in 1907. When I established the genus Ptilometra I said 

 that "I had at first isolated Alecto macronema, making it the type of Ptilometra and 

 including the other species [anthus, longicirra, and macropoda] in the genus Astero- 

 metra with Antedon macropoda as the type, but further study has led me to combine 

 the two, at least for the present." However, early in 1908 Aslerometra, with the 

 genotype Antedon macropoda, was included in a key to the genera of the family Ante- 

 donidae. 



Since 1918 when Asterometra magnipeda, was transferred to Pterom.etra the genus 

 Asterometra has been accepted in its present status. 



KEY TO THE SPECIES IN THE GENUS ASTEROMETRA 



a 1 . Elements of the division series and first two brachials with median keels or tubercles, or at least 



a narrow raised middorsal line. 



6'. Elements of the division series and first two brachials with a continuous median keel. 

 c 1 . Keels on the elements of the division series and first two brachials high and conspicuous. 

 d 1 . Keels on the elements of the division series and first two brachials with the crest strongly 

 convex in profile view so that the profile of the lower part of the animal is formed by a 

 series of scallops (from the Kei Islands and the Sahul Bank westward to Bali; 73-183 



meters) mirifica (p. 434) 



<P. Keels on the elements of the division series and first two brachials with the crest straight 

 in profile view and parallel with the longitudinal axes of the ossicles (Philippine Islands 

 and southern Annam; 80 [?72]-146 meters) cristata (p. 437) 



