39 1 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



Gislen said that it seemed to him rather unfortunate to characterize the genera 

 within the family Mariametridae on the basis of the relationships between the relative 

 lengths of the proximal pinnules, P,, P 2 , and P 8 , as has been done in the case of Liparo- 

 metra, Lamprometra, and Dichrometra, which surely are very closely allied. It cannot 

 be denied that these three genera are very closely related and that certain individuals 

 are not always readily placed generically merely by reference to the proximal pinnules. 

 Dr. Hubert Lyman Clark also wrote that he was somewhat inclined to question the 

 desirability of recognizing these three very closely allied genera. Yet Liparometra, 

 Lamprometra, and Dichrometra appear to represent definite generic types, which are 

 most obviously and readily differentiated from each other by the interrelationships 

 between the proximal pinnules when these are fully and typically developed. 



The species of Mariametridae are especially characteristic of the region from 

 southern Japan to Polynesia, northern Australia, and east Africa. Two genera, 

 Stephanometra and Lamprometra, occur from the Philippines and Polynesia to north- 

 ern Australia and east Africa; one, Dichrometra, ranges from southern Japan to the 

 Admiralty Islands and New Guinea and westward to east Africa; one, Liparometra, 

 is found from southern Japan to the Tonga Islands and the Lesser Sunda Islands; 

 one, Mariametra, occurs from southern Japan to Amboina and the Lesser Sunda 

 Islands; one, Oxymetra, occurs from the Philippines to New Britain and westward to 

 Ceylon, and one, Pelometra, is known only from Amboina. 



Like the species of the family Himerometridae, the species of Mariametridae are 

 especially characteristic of the littoral and sublittoral regions. Of the seven included 

 genera, five occur along the shore line. The two that have not as yet been taken in 

 shore collecting are Mariametra, occurring in 40-153 meters, and Pelometra, known 

 from only a single specimen dredged in 91 meters. Four genera, Oxymetra, Pelo- 

 metra, Liparometra, and Lamprometra, are not known from a greater depth than 95 

 meters, though three, Stephanometra, Mariametra, and Dichrometra, extend down to 

 more than 150 meters, the last having been brought up from 245 meters. 



History. — The family Himerometridae, which I established in 1908, was on 

 June 25, 1909, restricted by the removal of Cenometra and Cyllometra to the new family 

 Colobometridae, which was not at the time denned. On September 14, 1909, it was 

 further restricted by the establishment of the family Pontiometridae for the reception 

 of the single genus Pontiometra, and at the same time was divided into three subfami- 

 lies, Himerometrinae, Stephanometrinae, and Mariametrinae. 



In my paper on the systematic position of the genus Marsupites published on 

 June 24, 1911, the families Stephanometridae, Pontiometridae, and Mariametridae 

 were included in the families belonging to the suborder Oligophreata, the two last 

 being here mentioned as families for the first time. 



In a paper on the recent crinoids of Australia published on August 17, 1911, I 

 formally divided the family Himerometridae as previously understood into three 

 families, the Himerometridae, Stephanometridae, and Mariametridae (see p. 184). 



In my memoir on the crinoids of the Indian Ocean published in 1912 I recognized 

 the family Stephanometridae, with the genera Oxymetra and Stephanometra, the family 

 Pontiometridae, with the genera Pontiometra and Epimetra, and the family Mariame- 

 tridae, with the genera Selenemetra, Mariametra, and Dichrometra. 



