MUSEUM OF COMPARATIVE ZOOLOGY. 



67 



Disk liigh. Basal under arm- 

 plates about as long as broad. 

 Arms high and rounded, with 

 very short spines. Side arm- 

 plates not meeting below witliin 

 disk. Side mouth-shields small, 

 and at inner jioint of mouth- 

 shield. Many tentacle-scales. 

 (Typeo/0. bullata.) 



Interbraehial 

 space, below, 

 covered almost 

 entirely by the ^ 

 large moutli- f 

 shields andgen- 

 ital scales. 



Three minute, evenly spaced 1 



Uisk-scales above ! 0. hidlata 



Wyv. TLom. 



Mouth-shield 

 and genit-al 

 scales large and 

 conspicuous, ■ 

 but not cover-- 

 ing the central 

 margin of the 

 inter brachial 

 space. 



arm-spines. i^i3iv.-ouun.-3aui/>c , 

 rounded and of various sizes, [ 

 witli large mai'ginal plates. J 

 Three small tapering arm- I 

 spines. Disk covered above I 

 by a rosette of large angtilar ' ^ ermrtxii. 

 primary jilates, radial shields, r^- tonocra. 

 and a few large interbraeliial 

 I. i)lates. J 



Six minute nrm-siiines. First ' 

 under arm-jilate broader than 

 long ; those beyond longer than 

 broad. Radial shields sepa- 

 rated within by a cluster of 

 large scales. 



Four or five minute arm- 

 spines. Under arm-p!ates 

 longer than broad. Iladial 

 shields separated at inner ends I 

 by a single scale. J 



Three or four minute, wide- I 



)-0. ornata. 



■ 0. sculptilis. 



■ 0. variabilis. 



ly spaced arm-spines. Jlouth- 

 shield trefoil, with a pointed f 

 lobe inward. J 



Three minute arm-spines, "j 

 high up. Radial shields j 

 rounded, separated by one I ^ j^tn^fi 

 scale within. One large mar- ! "• -^^w'*- 

 ginal plate with small scales 

 about it. 



\o. lie 



re- 1 



ial >0. rai 



>0. un 



Three minute arm-spines. Disk covered by 

 small irregular scales, small sejiarated radial 

 shields, and verj- large mouth-shields. 



Two minute arm-spines. Mouth-shield tre- 

 foil. Under arm-plates axe-shape. Radial 

 shields small and rounded. 



Four minute, blunt ann-spines. Disk-plates 

 rough and lumpy, with rosette of large prima- 

 ries. Under arm-plates pent^igonal. 



Eleven short, pointed, close-set arm-spines. 

 Mouth-shields trefoil. Under arm-plates squar- 

 ish. Al)out eight tentacle-scales to each pore 

 within the disk. 

 Basal under arm-plates, beyond the second, about as long as broad, squarish, 

 and with water-pores between tliem. Arms high, with swollen upper ann-jilates 

 and very small sjiines. Upper disk covered in great part by a rosette of primary 

 plates and by radial shields. 



Disk covered with much-swollen lumpy plates. Genital scales w^ide, thick, and 

 in a single piece. Basal under arm-jilatcs longer than wide. Papillae of arm-comb 

 short, flat, close-set, and with rounded ends. 



Disk-plates high and excessively swollen. Upper arm-plates rising in a high 1 q j^j^deroso. 

 sharp ridge. Arm-spines minute, close-set, and like little blocks. J ' '^ 



>0. minuta. 

 fO. incrmis. 



0. lapidaria. 



0. solida. 



h 



riigosa. 



Interbraeliial space below covered by only one or two plates besides the genital 

 scales. Upper ann-plates rudimentary or wanting. Tcutacle-pores of arm with 

 only one rounded scale. 



Disk thick, and covered with thin smooth scales. No arm-eonib, nor papillie 

 along genital openings. Basal under arm-plates, beyond the second, short and 

 wide. 



Side mouth-shields large and 

 ovoid. Radial shields and 

 jirimary plates circular and 

 similar. 



Side mouth-shields small. 

 Mouth-shield broader than 

 long, with a peak inward. 



Disk-plates irregular and 

 humpy. A group of fiapilliC 

 near the arm, on margin of in- 

 terbraeliial space. 

 A small arm-comb. Side mouth-shields very 

 narrow. 



Disk and arm -plates thick, 

 swollen, and closely soldered. 

 Mouth-pajiilhe and scales of 

 mouth-tentaclts thick, squar- 

 ish, irregular, and crowded. • 

 Arm-spines minute, with tenta- 

 cle-scales similar in form, and 

 standing only on side arm-plate, 

 inside the pore. 



No true arm- 

 comb. 



0. Deshayesi. 



i 0. ino 



0. confragosa. 



