A MONOGRAPH OF THE EXISTING CRINOIDS 347 



Thermal range. From 8.67 C. to 17.22 C. 



Remarks. The species of the family Calometridae are very distinctive, the highly 

 characteristic PI, the solidly plated and more or less globular disk, which is easily 

 detached, the highly developed side- and covering-plates, and the stiff pinnules 

 making their recognition easy. Internally, the crescentic articular faces of the 

 radials and the greatly reduced muscular fossae are almost unique. The delicate 

 yellow and violet that characterize many species in life is otherwise found only in 

 the genus Homalometra (Himerometridae) ; but some species are, or may be, wholly 

 yellow, or yellow and brown, or even mostly brown. 



On the basis of our present fragmentary knowledge the five included genera, 

 Reometra, Pectinometra, Neometra, Gephyrometra, and Calometra, appear to be well 

 characterized. 



History. The name Calometridae was first mentioned, with no indication of its 

 significance, in a list of the families included in the suborder Oligophreata published 

 in 1911. Later in the same year I said that I had "created a new family Calome- 

 tridae containing four genera for the numerous species which I formerly placed in 

 Calometra." In 1912 the family Calometridae was denned, and Calometra, together 

 with the new genera Oreometra ( = Reometra), Neometra, Gephyrometra, and Pectino- 

 metra were assigned to it. Since then the status of the family has remained unchanged. 



KEY TO THE GENERA OF THE FAMILY CALOMETRIDAE 



a 1 . IIBr series 4(3 + 4); proximal cirrus sockets encroaching on the surface of the radials (Queens- 

 land; 46-47 meters) . Keometra (p. 347) 



a 2 . IIBr series 2, or with 10 arms only; proximal cirrus sockets not encroaching on the surface of 



the radials. 

 b 1 . Pz or Pa or both considerably longer than, usually from hah' again to twice as long as, the 



earlier genital pinnules, and more or less enlarged and stiffened; more than 15 arms. 



c 1 . Division series in apposition with those on each side either directly or through more or 



irregularly developed lateral extensions; proximal portion of the animal compact, the 



sides in profile making a relatively small angle with the dorsoventral axis (Andaman 



Islands to Celebes and the Philippines, and northward to southern Japan; 155 [?115] 



450 meters) Pectinometra (p. 375) 



c 2 . Division series, at least beyond the IBri, very widely separated, the sides of the ossicles 

 smooth and without lateral extensions; division series always making a very large angle 

 with the dorsoventral axis, sometimes being practically at right angles to it. 

 d 1 . Interradial extensions of the radials broad, separating widely the bases of the IBn; lower 

 pinnules comparatively stout (Andaman Islands and the western coast of Australia 

 to the Philippine Islands and southern Japan; 20-600 meters) Neometra (p. 355) 

 d 2 . Interradial extensions of the radials not developed, or if present narrow and not sepa- 

 rating the bases of the IBri; lower pinnules very slender (southwestern Japan to 



southern Annam; 5-174 meters) Gephyrometra (p. 351) 



b-. Pi and the following pinnules comparatively short, subequal in length; 10-15 arms (Kei Islands 

 to the Moluccas and northward to southern Japan; 100-439 meters) __ Calometra (p. 385) 



Genus REOMETRA A. H. Clark 



Oreometra A. H. CLARK, Zool. Anz., vol. 39, No. 11/12, 1912, p. 421 (occurs in the combination 

 Oreometra mariae, a nomen nudum); Crinoids of the Indian Ocean, 1912, p. 10 (absent from 

 Japan; reason), p. 58 (in key), p. 179 (diagnosis; genotype 0. mariae, new species). H. L. 

 CLARK, Biol. Results Fishing Experiments F. I. S. Endeavour, vol. 4, pt. 1, 1916, p. 21 (dis- 

 cussion). A. H. CLARK, Proc. Biol. Soc. Washington, vol. 47, 1934, p. 14 (preoccupied; replaced 

 by Reometra). H. L. CLARK, Echinoderm fauna of Australia, 1946, p. 54 (history). 



