PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 289 



conspicuously so, with the spinosity on the outer brachials tending to spread over the 

 dorsal surface in the form of a triangle with the apex proximal. 



The number of brachials to each arm in a large specimen of Florometra asperrima is 

 330, and P. H. Carpenter gives "more than 300" for large individuals of Heliometra 

 glacialis; there are half as many, or something over 150, in large specimens of Proma- 

 chocrinus kerguelensis in which there are twice as many arms. 



Syzygies occur between brachials 3+4, 9 + 10, 14 + 15 or 16 + 17, and distally at 

 intervals of normally 3 or 4 muscular articulations, this number being quite irregular 

 in Promachocrinus as is usual in multibrachiate types. 



Except in Promachocrinus kerguelensis, in which the number of arms varies from 

 10 to 23 (23, 22, 20, 19, 18, 17, 16, 12 and 10 having been recorded) but is almost in- 

 variably 20 in fully developed individuals, any departure from the normal number 

 of 10 arms is exceedingly rare. Only Florometra serratissima has been found with 11 

 arms as the result of the occurrence of a single IIBr 2 series, while another specimen of 

 the same species has been taken with a IIBr 2 series, the distal element of which was 

 not axillary. Individuals with 9 arms pathological in character have been reported 

 in Heliometra glacialis and in Florometra serratissima. 



Throughout this subfamily the proximal pinnules are singularly uniform in structure. 

 P! is always long and flagellate, composed of 30 to 82 (usually 50 to 60) segments which 

 are basally broader than long, then about as long as broad, with the corners cut away 

 giving flexibility, and the dorsal edge in the outer portion swollen or produced resulting 

 hi a serrate profile which may be so marked as to suggest the combs of the Comasteridae. 

 P 2 usually resembles P : and is of about the same length or very slightly longer with 

 somewhat fewer but slightly longer segments; in Anthometra, however, it is only about 

 half as long as Pj with less than half as many elongated segments and this condition 

 may be approached in Promachocrinus. P 3 is almost always shorter and slightly 

 stouter than PI and P 2 with fewer and more elongated segments; but in well developed 

 examples of Heliometra glacialis or of Florometra asperrima it may be similar to P 2 or 

 even longer. P 4 is usually shorter than PI and P 2 with fewer, more elongated segments, 

 resembling P 3 unless P 3 resembles P 2 ; but hi exceptionally fine specimens of Florometra 

 asperrima it may be similar to P], P 2 and P 3 , and longer than any of them. P s resembles 

 P 4 and is usually shorter; hi the most developed specimens of Florometra asperrima 

 it is slightly shorter than Pj. 



Briefly stated, hi this subfamily the oral pinnules are long and flagellate, composed 

 of very numerous short segments which are not longer than broad. Pj may be the 

 only oral pinnule, as hi Anthometra and sometimes in Promachocrinus, but usually P, 

 and P 2 are modified as oral pinnules and are similar, with P 3 shorter and composed of 

 much longer segments. Rarely, in the largest species, P 3 is also an oral pinnule, and 

 it may be even longer than P, and P 2 , while very exceptionally P 4 may also be an 

 oral pinnule. 



The middle and distal pinnules show little variation. The distal pinnules are 

 slender, very nearly as long as the oral pinnules and composed of about half as many 

 segments, most of which are usually about twice as long as. broad with the distal ends 

 fringed with spines. 



The gonads are very long and fusiform. 



The deposits along the ambulacral grooves of the pinnules hi Florometra consist 

 of slender to stout rods, straight or slightly curved, with the ends usually roughened 



