195 



This species is distinguished from A. geminata, by the sliape 

 of the mouth-shields and of the upper and lower arm-plates, and 

 in having the mouth-papillas of the same size ; from A. Chilensis, 

 by having two tentacle-scales, instead of one. 



Locality, Monterey, Cal. Mr. Sayla. 



Smithsonian Institution, No. 1054, and No. 10G3 (?). 



No. 1063 is from Puget Sound, and may be another species. 

 The spines are blunter, the under scales of the disc larger and 

 less crowded, and the under arm-plates rather more rounded. 

 More specimens will settle the question. 



Amphiura urtica, (Lyman,) sp. nov. 



Description of a Specimen. Diameter of disc, 6 millira. 

 Outer side of mouth-shield to outer corner of opposite mouth- 

 slit, 2 millim. Width of arm without spines, .8 millim. Length 

 of arms, about eleven times diameter of disc, (a specimen having 

 a diameter of disc 5.5 millim. had 55 millira. length of arm). 

 Mouth-papillae rounded and bead-like. Mouth-shields nearly 

 square, with an angle directed inward ; outer angle truncated and 

 making a slight peak ; other angles slightly rounded. Length to 

 breadth, .5 : .5. Side mouth-shields not meeting within. Upper 

 arm-plates irregular oval, outer side less curved than inner side ; 

 length to breadth, .5 : .7. Under arm-plates scarcely touching 

 each other ; inner one five-sided, the rest nearly square, with a 

 strong notch in the outer side ; length to breadth, .4 : .4. Scales 

 of disc fine and even ; some of those near maro^in of disc bearinor 

 very fine prickles on their edges. Primary plates not conspicu- 

 ous. Arm-spines 3, about as long as the joints, delicate, sharp, 

 regularly tapering. Tentacle-scales 2, both of them small and 

 delicate. Color, in alcohol : upper and under surface of disc dark 

 greenish gray, with a margin of light ; arms light straw-color. 



Variations. The mouth-shields vary in shape to an unusual 

 degree ; sometimes they have a strong peak without, and again 

 none at all ; they may be nearly rectangular, or almost oval, and 

 some are not far from round. The under arm-plates may be 

 more or less pentagonal ; but, in the adult, most; of them are 

 nearly square. The young, with a disc 2.5 millim. in diameter, 

 have the under arm-plates pentagonal, with a deep notch in their 

 outer side, and separated by the side arm-plates ; they have also, 



