116 CLARK! NEW GENERA OF ECHINODERMS 



and A nalcidometra are related to Oligometrides more closely than to 

 any other type. 



The third-fifth segments of the genital pinnules are more or less 

 expanded to protect the genital glands; there is a single median trans- 

 verse ridge of moderate height on the cirrus segments; Pi, though 

 longer and stouter than P 2 , is not exceptionally so. 



Austrometra thetidis (H. L. Clark), the only species of the genus, 

 occurs off the coast of New South Wales in 55 to 56 fathoms. 



Cotylometra, new genus 

 Genotype. — Oligometra gracilicirra A. H. Clark, 1908. 

 This genus of Colobometridae in general resembles Oligometra; 

 but there are 30 or more cirrus segments of which only the basal bear 

 transverse ridges, these after the proximal fourth of the cirrus trans- 

 forming into very long dorsal spines, and P 2 has at most 12 segments 

 instead of at least 15. 



The single species of this genus, Cotylometra gracilicirra (A. H. 

 Clark), ranges from the Andaman Islands to the Malay Archipelago 

 and the Philippine Islands in from 44 to 49 fathoms. 



Daidalometra, new genus 



Genotype. — Antedon hana A. H. Clark, 1907. 



A genus of Thalassometrinae (Thalassometridae) in which the centro- 

 dorsal is small, low, hemispherical or thick discoidal, the broad dorsal 

 pole beset with irregular rather long spines, the sides bearing 10 closely 

 approximated columns of cirrus sockets of from one to three (usually 

 two) each; the cirri are XII-XX, 51-75, slender, from about one-half 

 to three-fourths as long as the arms; the longer proximal segments are 

 usually about three times as long as broad ; the basal three or four seg- 

 ments bear dorsally a fine median carination ending distally in a small 

 but prominent spine; the disk is moderately plated; the division series 

 and arms in general are as in Stenometra, but the arms are only from 10 

 to 12 in number, and the earlier brachials have only a faint low median 

 keel; the pinnules are as in Stenometra. 



Of the two species referable to this genus, one, Daidalometra hana 

 (A. H. Clark), occurs off southwestern Japan in between 107 and 139 

 fathoms; the other, Daidalometra acuta (A. H. Clark), was dredged 

 south of Timor in 40 fathoms. 



Mariaster, new genus 



Genotype. — Johannaster giganteus Goto, 1914. 



This new genus belongs to the subfamily Goniasterinae of the family 

 Goniasteridae. 



The general form is stellato-pentagonal, with greatly produced, nar- 

 row, evenly tapering rays which are somewhat more than two and one , 



