54 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 6l 



elongated in the outer portion ; P 3 is larger than P 2 , being much the 

 largest pinnules on the arm, 13 mm. long with from eighteen to twenty 

 segments, of which the distal are much elongated, three times as long 

 as broad ; the pinnule becomes very slender distally, and the ends of 

 the component segments are slightly swollen, though not projecting 

 nor spinous : P 4 is small and weak, 4.5 mm. to 5 mm. long, the outer 

 segments much elongated and with somewhat swollen ends ; P 5 is 

 slightly longer than P 4 ; the following pinnules are similar to P 5 , 

 gradually becoming more slender and increasing in length distally. 

 Remarks. — The pinnulation of this species is not very* different 

 from that of /. parvicirra, but the cirri are very much larger than 

 those of that species. 



IRIDOMETRA SCITA A. H. Clark 



i. Billiton. — Two specimens. 



2. Macclesfield Bank; 35-41 fathoms. — One specimen. 



IRIDOMETRA NANA (Hartlaub) 



I. Male, Maldives. — Five specimens; the largest has an arm 

 length of 60 mm. 



HYBOMETRA, new genus 



Genotype. — Hybometra senta, new species. 



The characters of the genus are included with those of the type 

 species in the following description. 



HYBOMETRA SENTA, new genus and species 



Description. — The general appearance of the animal resembles 

 that of Florometra magellanica when not quite fully grown, but 

 the centrodorsal is rounded conical as in Hathrometra prolixa; the 

 brachials are very strongly overlapping with produced and very 

 highly spinous distal edges ; syzygies occur between the third and 

 fourth brachials, again between the ninth and tenth and fourteenth 

 and fifteenth, and distally at intervals of three (often four) oblique 

 muscular articulations. 



Cirri lost. 



The ten arms are 90 mm. long ; the distal edges of the brachials 

 overlap very strongly, and are exceedingly spiny. 



No P x preserved ; P 2 is 9 mm. long, very slender, but very stiff 

 and spine-like, with about fifteen segments, of which the first is rather 

 large, half again as broad as long, the second is somewhat longer, 





