78 



with paler bands on tlie arms; the lower surface much paler 

 (Gairett). 



This species is distinguished from O. cincta hj shorter mouth-shields 

 and much longer arms. 



Ophiocoma Tartarea, Lyman. 



Ophiocoma erinaceus (pars?) Ltk. Addit. ad Hist. Oph. 164. 



Special marks. Black. Arms about five and a half times as long 

 as diameter of disc. Upper spines slender and much longer than the 

 rest ; sometimes four and a half times as long as an under arm-plate. 

 Two tentacle scales. Interbrachial spaces below not granulated. 



Description of a specimen. Diameter of disc 25 millim. Breadth of 

 arm without spines 4 millim. Length of arm 132 millim. Tooth- 

 papillae fourteen to eighteen, sometimes in transverse rows of three ; 

 sometimes irregularly placed. Teeth stout, thickened, four in num- 

 ber. Mouth-shields longer than broad, broader without than within, 

 corners all rounded ; outer side curved, or made up of three lines ; 

 lateral sides re-enteringly curved ; length to breadth 3.3 : 2.8. Side 

 mouth-shields triangular, small, broad, lying entirely on the sides of 

 the mouth-shields. Under arm-plates considerably broader than long ; 

 a little way from the disc, regularly hexagonal ; length to breadth 

 (14th plate) 1.9 : 2.5. Upper arm-plates broader than long, some- 

 what affected in shape by the number of arm-spines ; most are either 

 hexagonal or oval hexagonal, with very sharp lateral corners ; length 

 to breadth (13th plate) 1.9:4.2. Disc very regularly and finely 

 granulated above, about 14 to a square millim. ; below interbrachial 

 spaces naked, showing the fine scales. Arm-spines near base of arm 

 alternating five and four, rarely six ; further out four and three ; at 

 the tip of the arm only three ; upper spine very long, slender, cylin- 

 drical, slightly tapering, sometunes a little curved; other spines 

 smaller ; within the disc the lowest spine is often much flattened and 

 widened at its end ; lengths to that of under arm-plate 9, 6.8, 5.5, 

 5.5, 3.5, 3.5: 1.9. Tentacle scales two, nearly to the tip of the arm; 

 outside one oval, inside one more or less irregular. Color, in alcohol, 

 black ; the under surface of the arms having a brownish shade. 



Variations. This species presents some differences in the lengths 

 of the arm-spines, but very little in their character. The range of 

 variation is very much as in 0. Busei. The specimen above described 

 had spines of the maximum length. Another large specimen, with 

 a disc of 27 millim. and arms of 150 millim., had the spines as fol- 

 lows : 6, 5.5, 4, 3.3, 2.7. The spines of another were, 5.8, 4.5, 3.5, 

 2.8, 2.5 ; the disc being 22 millim. A partly grown specimen from 

 Kingsmill Island belonged apparently to this species ; the disc was 

 20 millim. in diameter, and the spines were 5, 3, 2.6, 2.6, 2.6. 



This seems to be the species described by Dr. Liitken as identical 



