A MONOGRAPH OF THE EXISTING CRINOIDS 89 



1915, p. 214; Unstalked crinoids of the Si&oja-Exped., 1918, p. 130. H. L. CLARK, The echino- 

 derm fauna of Torres Strait, 1921, p. 23. GisLfen, Vid. Medd. Dansk Naturh. Foren., vol. 83, 

 1927, p. 29. 



Oligometrides (part) A. H. CLARK, Unstalked crinoida of the Stfcopa-Exped., 1918, p. 126. 



Iconometra A. H. CLARK, Journ. Linn. Soc. (Zool.), vol. 36, No. 249, May 1929, pp. 635, 643 (diag- 

 nosis; genotype /. speciosa, new species). H. L. CLARK, Echinoderm fauna of Australia, 1946, 

 p. 48 (in key), p. 49. 



Diagnosis. A genus of Colobometridae in which P,, P 2 , and P 3 are similar, 

 elongated, stiffened, evenly tapering, and composed of segments which beyond the 

 first two are much elongated; P 2 is longer than PI or P 3 ; P a is present; the cirri are 

 rather stout and are composed of 15-23 short subequal segments none of which are 

 longer than broad, bearing dorsally a more or less marked transverse ridge situated 

 at or very near the proximal end; the arms are 10-20 or more in number; the division 

 series, which are always 2, are broad and are in lateral contact except for water pores; 

 and the brachials are broader than long, except hi the outer portion of the arms. 



Genotype. Iconometra speciosa A. H. Clark, 1929. 



Geographical range. From Sagami Bay, Japan, and the Philippine Islands 

 southward to Torres Strait and westward to Solor Strait and the coast of Annam. 



Bathymetrical range. From the shore line down to 148 meters. Three of the 

 species (bellona, anisa, andjaponica) are littoral, extending from the shore line down to 

 probably not,more than 50 meters, but the other two (speciosa and marginata) are 

 known only from depths greater than 100 meters. 



Remarks. The genus Iconometra is very closely related to the genus Oligometrides, 

 with which it agrees in having P,, P 2 , and P 3 similar, stout, stiffened, and smooth, 

 and usually also in having the dorsal transverse ridge on the cirrus segments near the 

 proximal end. In Oligometrides PI is longer and proportionately stouter than the 

 pinnules following, and the cirrus segments bear dorsally a second prominent trans- 

 verse ridge, or row of tubercles, or paired tubercles, near the distal end. In Icono- 

 metra P 2 is longer and proportionately stouter or at least stouter than P,, and in 

 those species in which the transverse ridge is proximal the second transverse ridge 

 near the distal end of the cirrus segments so characteristic of Oligometrides is typically 

 wholly absent, though in certain cases it may be indicated, or even feebly developed, 

 on some of the outer segments, though never on the outermost ones. 



While agreeing in its pinnulation closely with the other species, I.japonica has the 

 dorsal transverse ridge on the cirrus segments at first near the distal end, later becom- 

 ing median, in this respect approaching the species of Oligometra. Occasionally, 

 also, the third-fifth segments of the genital pinnules in this species are slightly broad- 

 ened, so that it approaches the species of Avstrometra and Analcidometra. 



Except for /. japonica the species of this genus as herein understood are so 

 extraordinarily alike in the details of their pinnule and cirrus structure as strongly to 

 suggest that they are really only forms of the same specific type. All of them are 

 rare, and done is sufficiently well known to enable us to say anything very definite 



about it. 



It is possible indeed quite probable that speciosa will eventually turn out to 

 be the same as the previously described bellona. The differences between the two as 

 we know them at present appear to be well within the range of individual variation; 



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