174 OPHIOTHRIX PROPJNQUA. 



Ophiothrix propinqua Lyman. 



Ophiothrix propinqua Lyman. Proceed. Boston Soc. Nat. Hist., VIII. p. 83. 1861. 



Special Marks. — Disk sparsely granulated, and covered above with 

 narrow scales, which form five to seven radiating rows in the interbra- 

 chial spaces. Radial shields naked. 



Description of a Specimen. — Diameter of disk, H™™- ^ width of arm 

 without spines, 1.6°"" ; length of arm, 125°"". Tooth-papillas standmg 

 nearly on a level with each other, thirteen to fifteen, in horizontal rows 

 of two, or more commonly three ; the lowest ones smallest. Teeth 

 four, very thick and stout, the highest one smallest. Mouth-shields 

 small, irregular oval, or oval heart-shaped, broader than long ; length 

 to breadth, .7 : 1.2. Side mouth-shields short and wide, not meeting 

 within. Under arm-plates oval, broader than long, the outer side a 

 httle re-enteringly curved ; length to breadth (twelfth plate), .6 : .8. 

 Upj^er arm-plates pointed oval, much broader than long ; length to 

 breadth, .6 : 1.5. Disk covered above with narrow, elongated, rather 

 indistinct scales, arranged in parallel, radiating rows ; from five to 

 seven such rows in each interbrachial space, and a single row of three 

 or four scales between each pair of radial shields ; these scales bear 

 a few rough grains ; outside each radial shield a row of roundish 

 scales ; interbrachial spaces below covered with very short spines. 

 Eadial shields smaller than usual, regular triangular, quite naked ; 

 length to breadth, 2.8 : 1.6. Arm-spines near base of arm, from five 

 to seven, the two or three lowest very small, the larger ones swelled 

 at the tip ; lengths to that of under arm-plate, 2.2, 2.5, 2.2, 1.1, .6 : .6. 

 Tentacle-scale very small, somewhat pointed. Color, in alcohol : above, 

 disk bright Prussian-blue, varied with whitish ; outer tips of radial 

 shields white ; arms obscurely banded with paler and darker blue ; a 

 longitudinal stripe of dark blue along the middle, and a small white 

 spot between each pair of upper arm-plates ; below, interbrachial s^^aces 

 dark blue ; mouth parts and under arm-plates nearly white. 



Variations. — Another specimen had the disk of a more intense blue, 

 and the white spots on the arms were nearly wanting. 



This species approaches 0. nereidina, but has more rows of scales on 

 the back of the disk ; the arms, also, are proportionately shorter. 



