AMPIIIURA TENERA. 



123 



This widely-spread little creature, extendin<^ from the Mediterranean 

 on the east, to Massachusetts ]5ay on the west, possesses a high hiterest 

 as being viciparoiis, a I'act first noticed by Professor De Quatrefao-es 

 (Coniptes Kendus de TAcadeniie, XV. p. 799, 1842), and afterwards 

 more fully treated by Dr. Schultze (Midler's Archiv., p. oT, 1852). I 

 myself found a good number, during the month of June, in the basin 

 of Arcachon, s(nith of Bordeaux. They lived just below low-water-mark, 

 among bits of broken shell. On being captured, the gravid indivicbials 

 would often cast off their disk, from which would wriggle out numerous 

 orange-colored young ! 



LIST OF SPECIMENS. 



Amphiura tenera Lutken. 



Amphiura tenera LiJTKEX. Addit. ad Ilist. Ojjh., j). 124. 



Special 3Iarl's. — Length of arm usually about four times the diam- 

 eter of the disk. Middle arm-spine swelled at the base. 



Description of a Specimen. — Diameter of disk, 3.2""°" ; from outer 

 side of mouth-shield to outer corner of opposite mouth-slit, 1.3""°' ; width 

 of arm without spines, .4""°- ; length of arm, 10.5"™" ; distance from outer 

 side of mouth-shield to inner points of mouth-papilla?, to that between 

 outer corners of mouth-slits, .6 : .6. Mouth-papilla}, three on each side ; 

 outermost one wider than both the others together, flat, with a curved, 

 cutting edge ; two mner ones separated, nearlj^ equal, small, rounded, 

 bead-like ; innermcst one of all running upwards to the teeth. Teeth 

 four, longer than broad ; two uppermost ones flat, squarish, thin ; two 

 lowermost the same, Ijut more rounded, tapering, and pointed. Mouth- 

 shields heart-shaped, with straight sides, and a sharp point turned 



