ASTEROIDEA 207 



b^. Gonads numerous, in series on either side of base of ray. 



c^. Disk plates small, bearing one to several small spinelets; on the ray only one lateral 

 or marginal spine (never a comb of several); no intercostrl embryonic plates; 

 furrow spine or spines present. 



d^. Proximal subambulacral spine or spinus acicular; second subambulacral when 

 present at adoral end of plate; adambulacral armature not dense and crowded. 



Brisinga. 



d'-. Proximal subambulacral spines with modified, capitate, often truncate tip; a 

 second, prominent subambulacral regularly present near aboral end of plate, 

 armature crowded. Craterobrisinga. 



c^. Disk plates large, with 1-3 fairly large acicular spines; a vertical series of 4 con- 

 spicuous lateral spines to each successive skeletal arch of ray; integument between 

 costae with spaced embryonic plates; no furrow spinelets; i prominent subambula- 

 cral with modified capitate tip throughout genital region. Bnsingaster. 



A comparison of Figs. 2 and 3, 5 and 7, indicates a considerable difference in the form 

 of mouth-plate. In descriptions of species only the exposed oral face of the plate is 

 considered, whereas the dorsal and lateral extensions which are intimately concerned in 

 the structure of the ring are really of greater importance. With modifications of the 

 mouth-plates are linked changes in the first ambulacrals. 



The odontophore exhibits considerable individuality. 



Even in genera, having the general arrangement of first adambulacrals and marginals 

 indicated above, the marginals differ in size and posture and the distal joint of the 

 adambulacral may be muscular or non-muscular. 



The development of muscles between adjacent mouth-plates (Fig. H, 6, o', 0") varies in 

 different genera. 



Odinella nutrix sp.nov. 



(Figs. G, 1-6; H, 1-9; Plates XIV, XV, XVI, figs, i-ii ; Plate XVII, figs. 1-3) 

 Diagnosis. Rays 11-14, usually 12 or 13. R 75-80 mm., r 7 mm. (type). Rays 

 abruptly swollen at base into a specialized genital region with numerous irregularly 

 placed abactinal spines, which dorsolaterally and laterally interlock with those of ad- 

 jacent rays and sometimes form permanent bridges, protecting, in axils of female, a 

 specialized brood chamber; beyond genital area, ray narrow, very flexible, with a series 

 of lateral, slender, spaced costae bearing 3 or 2 acicular spines immersed in ovoid 

 saccuU covered with pedicellariae ; i subambulacral spine with lateral succulus; i 

 suboral and 2-4 marginal oral spines ; disk small, sunken below level of the rays, the 

 spinelets devoid of pedicellariae; papulae on disk and genital region only ; pedicellariae 

 very small, the oral different in form from those of rays. A 12-rayed specimen (St. 123) 

 measures R 100 mm., r 7 mm.; br, at disk, 2-3-5 mm.; at middle of genital inflation 

 5-13 mm. ; at middle of R 3-5 mm. 



Description. The general appearance, well shown by the figures of entire specimens, 

 is highly characteristic and very different from that of any known Brisingid. In mature 

 specimens the genital region of the ray is inflated, irregularly spiny and papulose, in 

 close contact with adjacent rays, and slightly longer than width of disk. The distal 



lS-2 



