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AMPHIURA GEMINATA. 

 LIST OF SPECIMENS. 



Amphiura geminata Ldtken. 



Ophiolepis geminata LeConte. Proceed. Phil. Acad., V. p. 317. 1851. 

 Amphiura (Ophiolepis) getninata LiJTKEN. Addit. ad Hist. Oph., p. 122. 



Special Harks. — Arm-spines, near disk, four ; the second from below 

 a little rough and somewhat the largest. Lower arm-plates pentagonal. 



Bescrijition of a Specimen. — Diameter of disk*, 4""°- ; from outer 

 side of mouth-shield to outer corner of opposite mouth-slit, 1.7°"°' ; 

 width of arm without spines, .7°"°' ; length of arm, 35""- ; distance 

 from outer side of mouth-shield to inner points of mouth-papillaj, 

 to that between outer corners of mouth-slits, 1 : .7. Mouth-papillaj, 

 three on each side, in a continuous row ; outermost one broader than 

 both the others ; two inner ones very small, rounded, bead-like. Mouth- 

 shields longer than broad, shaped like a spear-head, with the point 

 inward ; inner lateral sides much longer than outer ones, which are 

 short and re-enteringly curved ; length to breadth, .5 : .3 ; sometimes 

 the mouth-shield is more blunt within. Side mouth-shields proportion- 

 ately rather large, triangular, not meeting within, sides often a little 

 re-enteringly curved. Under arm-plates broader than long, pentagonal, 

 with an angle turned inward ; sides nearly straight, outer corners 

 slightly rounded ; nearly, but rarely quite, separated by side arm-plates ; 

 length to breadth (tenth plate), .3 : .4 ; first plate rounded, compara- 

 tively large ; plates at tip of arm shaped much like the basal ones, but 

 more rounded, and inclining to a heart form. Side arm-plates encroach- 

 ing below pretty equally, from base to end of arm ; above, encroaching 

 less. Upper arm-plates regular, broader than long, oval, more curved 

 within than without, and tapering toward each side ; length to breadth 

 (eighth plate), .3 : .6. Disk-scales small, even, a httle larger near edge 



* This measure was taken from one of Dr. LeConte's 

 of the living animal probably measured not less than 5"°-. 



Iglnal specimens, when dry ; the disk 



