514 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



adambulacral plates given by me in connection with the original de- 

 scription (Fisher, 1906, pi. 48, figs. 2, 2a). In these figures only the 

 dwarfed inner subambulacral spines are shown. The adoral spinelet 

 appears never to be present. 



CRATEROBRISINGA EUCORYNE Fisher. 



Plate 143, fig. 3; plate 148, figs. 4-6; plate 149, fig. 2; plate 154, figs. la-c. 



Brisinga (Craterobrisinga) eucoryne Fisher, 1916&, p. 33. 

 Craterohrisinga eucoryne Fisheb, 1917/, p. 426. 



Diagnosis. — Eays 11. Related to 0. alberti (Fisher). Five or 6 

 inconspicuous rudimentary costae at base of ray, followed by 17 to 

 20 well-spaced prominent ridges occupying proximal third of ray; 

 numerous small integumentary spinelets, and about 3 inconspicuous 

 bands of pedicellariae between the costae, which are composed of 

 elongate elliptical plates, usually not compressed, bearing 1 or 2 

 spinelets in center; disk small, with crowded, rather long, solitary 

 spinelets giving a hirsute appearance; adambulacral plates proxi- 

 mally wider than long with crowded armature; first dozen plates 

 with also the slenderer of the 2 subambulacrals often truncate and 



slightly flaring ; typical formulae — -■ — I- / or -. — , ^. ; 2 (instead 



of 1) large subambulacral spines characteristic; each mouth plate 

 with 2 large pointed suboral spines. Breadth of disk=3^ times 

 width of ray at base (6 mm.) ; actino3tome=2 times same; height 

 of disk=| breadth of ray at base. R=2054-mm. r=10.5 mm. 

 (small section from tip of ray missing). 



Description. — Disk small, with an abrupt rounded border and 

 rather prominent, vertical, interradial plates. Disk covered with 

 relatively long, solitary, delicate, glassy spinelets, which by reason 

 of their thick saccular investment have usually a blunt papilliform 

 appearance and give a hirsute appearance to the disk. These spine- 

 lets are about 0.75 mm. long, are longest at center of disk, decreasing 

 to 0.5 mm. at the margin, and are spaced one-fourth to one-third 

 their length. The spinelets are frequently directed toward a com- 

 mon center forming conical groups resembling incipient spiniform 

 pedicellariae. Scattered among the spinelets are relatively few 

 forcipiform pedicellariae of small size. 



Ra3's relatively short, swollen on the costal region, which occupies 

 the proximal third of ray. At the base of ray are 5 or 6 incon- 

 spicuous costae, followed b}'^ 17 to 20 well-spaced, fairly prominent 

 costae, which in the midradial region are almost always distorted in 

 some way. The plates composing the ridges are not compressed. 

 Each plate is very distinct and is in form a long, slender ellipse, con- 

 stricted slightly in the middle where there is a short, upright, slen- 

 der, sharp spinelet (sometimes 2). Tlie surface of the plates is 



