139 



The ends of the basal rays are visible as prominent rounded dorsoventrally elongate 

 tubercles in the angles of the calyx. 



The distal borders of the radials are just visible beyond the edge of the centrodorsal ; 

 they are strongly concave, curving upward over the ends of the basal rays and meeting just 

 above them in the angles of the calyx ; they are slightly produced outward, and are continued 

 upward into very narrow interradial processes which entirely separate the IBr r 



The IBrj are very short, chevron shaped, slightly less in median than in lateral length ; 

 the proximal edge is slightly swollen, the lateral edges slightly turned ontward, straight, with 

 a low blunt tubercle at the distal and proximal angles and sometimes a second near the former ; 

 the median line of the ossicle is occupied by a very high narrowly rounded crest, which is 

 much higher proximally than distally. The IBr„ (axillaries) are irregularly rhombic, not quite 

 twice as broad as long, with the distal and lateral angles rather strongly produced; the proximal 

 half of the median line bears a narrowly rounded crest which is much lower than that on the 

 IBr^ this crest posteriorly is of the same height as the anterior end of the crest on the \Br l 

 which it adjoins; anteriorly it sinks gradually downward to the level of the general dorsal 

 surface of the ossicle; the proximal borders of the IBr. 2 are, except laterally, slightly thickened 

 and produced over the distal borders of the IBr,, and coarsely and obscurely scalloped; the 

 distal edges are slightly everted, but not otherwise modified. 



The IIBr series are 2, resembling the IBr series but without any tracé of carination or 

 modification of the proximal or distal borders; the IIB^ bears a broad ventrolateral process, 

 at the base nearly as wide as the segment, in height equal to about half the distance from 

 the lateral margin to the median line, outwardly rounded, sometimes with one or two coarse 

 low processes or blunt tubercles. 



The 20 arms, which are 70 mm. long from the border of the radials, resemble those 

 of the other species of the genus ; the brachials have rather prominent finely spinous distal ends. 



This individual only differs from the type of P. magnijïca (which is before me) in the 

 greater development of the keel on the IBr^ in the very faint keel on the IIBr series, and in 

 the slightly Jonger proximal cirrus segments. It is undoubtedly a young example of that species. 



A third specimen of this interesting form was dredged by the " Albatross'' at Stat. 5661, 

 in 180 fathoms in the Flores Sea (Cat. N° 35972 U.S. Nat. Mus.). 



IX. Family Thalassometridae A. H. Clark. 

 Key to the Subfamilies of the Family Thalassometridae. 



a 1 Pj shorter and smaller than P.,, but similar to. it (southern c o a s t 

 of Australia northward to southern Japan; 11 — 252 

 Metres) Ptilometrinae 



a 3 Pj larger and longer than P., (C a r i b b e a n Sea and the B ay 

 of B i s c a y southward to Ascension and T r i s t a n da 



