PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 293 



of spines on the dorsal surface though this may be less prominent on large specimens; 

 the proximal pinnules have the distal segments produced on the outer side, suggesting 

 a rudimentary terminal comb ; the middle and dist al pinnules have more or less elongated 

 segments; the centrodorsal is rounded conical or flattened hemispherical, sometimes 

 with a deep pit at the apex; the longest cirrus segments are often over twice as long as 

 wide; and there are 5 radials and 10 arms. 



Type species [by A.M.C.]. In 1914 Mr. Austin Clark named Antedon mariae 

 A. H. Clark, 1907, as the type species of Florometra (then considered to rank as a sub- 

 genus of the genus Promachocrinus) and listed a number of other species including 

 magellanica (Bell), 1882, as consubgeneric. This disposition was repeated in 1915, 

 when a diagnosis for Florometra was added. However, in 1913, at the very first 

 mention in print of the name Florometra, Mr. Clark only gave it in connection with 

 the species-group name magellanica. Under the rules of nomenclature, where publica- 

 tions before 1931 are concerned, the inclusion under a new generic (or subgeneric) name 

 of a valid species is sufficient indication to establish the new generic name with that 

 species as the type. The fact that Florometra was first mentioned as a subgenus is 

 immaterial. Florometra therefore dates from 1913 and Antedon eschrichti var. 

 magellanica Bell, 1S82, is its type species, by monotypy. The subsequent designation 

 of another species as type was unnecessary and has no validity. 



Geographical range. From the Southern Ocean and Cape Horn northward along the 

 western coast of South and North America to the southern Bering Sea, thence westward 

 to the western end of the Aleutian chain, and southward along the eastern and southern 

 coasts of Japan to the Korean Straits. 



I'^athy metrical range. From 11 to 1574 meters. 



Thermal range. From -1.85 to 13.50 C. 



Specific interrelationships within the genus [modified by A.M.C.]. The question 

 of which characters provide specific distinctions within this genus is still an open one, 

 particularly with regard to the four North Pacific species in which the centrodorsal, 

 cirri, arms and pinnules are singularly uniform in structure, and the only differential 

 characters seem to be found in the position of the third syzygy, the relative length of 

 the brachials, and the relative development of a dorsal extension of the basal segments 

 of the proximal pinnules, none of which features are of any special value in any other 

 comatulid group. 



The relative proportions of the proximal pinnules, a constant and reliable character 

 among most of the comatulids, is here less reliable for systematic purposes, for all the 

 species show to a greater or lesser extent the same diversity seen in Heliometra glacialis. 

 However, when size is also taken into account the number of pinnule segments may be 

 of significance. 



The proportions of the cirrus segments may also be of use, but bearing in mind the 

 variation found in the related genus Promachocrinus by John (1938) may not prove 

 reliable unless used in conjunction with other characters. The size of the dorsal spines 

 on the cirri can also be used in some cases, F. goughi exhibiting a minimum development 

 of these. 



At the other extreme, F. mawsoni has very prominent dorsal processes on the 

 distal cirrus segments like those of Solanometra antarctica which it also resembles in 

 the relatively short segments of the middle and distal pinnules, most of which are only 

 a little longer than broad. As discussed on pp. 340 and 419 I [A.M.C.] think it proba- 



