OPIIIURA CINEREA. 27 



Ophiura cinerea Lymax. 



Ophioderma cinereum Mull. & Troscii. Syst. Asterid., p. 87. 1842. 

 Ophiodcnna Antillarum Lutkkx. Addit. m\ Hist. Oph., p. 88. 



Specicd 3larks. — A large species. In adult, upper arm-plates much 

 broken ; mouth-shields broad heart-shaped ; niouth-papilhi3 crowded, 

 luunerous, and pretty equal (about t^Yenty) ; arms very round, ta- 

 ])ering. 



Dcficripfion of a Specimen. — Diameter of disk, 20"""' ; from outer 

 edge of mouth-shield to outer corner of opposite mouth-slit, 8""- ; greatr 

 est width of arm without spines, 4.2"""" ; length of arm, OV"""- ; distance 

 lioni outer edge of mouth-shield to inner points of mouth-papillae, to 

 that between outer corners of mouth-slits, 4 : 4.4. Mouth-papillae, nine- 

 teen to twenty-one to each angle of mouth (usually twenty), outer one 

 very long and slender, running above next one or two papilla?, when 

 mouth is tight shut ; two innermost ones, pointing to centre of mouth, 

 much stouter than others ; of remaining papillae, four inner ones some- 

 what weaker than four outer ones ; all papilla? crowded, pointed, rounded. 

 Teeth five, flat, somewhat blunt ; the uppermost one longer and sharper. 

 Mouth-shields short heart-shaped, point inw^ard, well rounded, length to 

 breadth, 1.8 : 2.2 ; madreporic shield more rounded, and somewhat larger, 

 near its centre a rounded depression ; side mouth-shields entirely covered 

 ))y granulation. Under arm-plates thick, strong, and finnly set ; bounded 

 hy a curved outer side, two long lateral sides a little re-enteringly 

 curved, two very short inner laterals, and an inner side, nearly straight ; 

 towards end of arm, each plate is an octagon, its lateral sides being very 

 long, and its outer and inner laterals very short ; first plate small, irreg- 

 ular oval, with a slight peak imvards, length to breadth, .8 : 1.4 ; second 

 plate, 1.2 : 1.4 ; eleventh plate, 1.2 : 1.4 ; about two thirds out on arm, 

 length to ])readth, 1.2 : 1 ; at tip of arm, plates nearly heart-shaped, with 

 point inward. Side arm-plates thick, compact, closely soldered with 

 surrounding parts, their outer edges very conspicuous by reason of 

 shortness of arm-spines ; not meeting above at all, and below onh^ at 

 very tip of arm. Upper arm-plates are all, with exception of first rudi- 

 mentaiy one, and a few' at tip of arm, broken in several pieces, irregular 

 in form, and varying in number from two to five, according to size of 

 plate ; each plate, considered as a whole, makes a belt across arm, of 

 which the inner side is shorter than the outer ; incision in disk embraces 

 first three plates, which are modified in shape accordingly ; fourth plate, 

 broken in four or five pieces, length to breadth, 1.2 : o.G ; about two 

 tbirds out on arm, some plates are found whole, but most are broken in 

 two or three pieces ; length to breadth. 1 : 2.6 ; close to tip of arm. 



