﻿AMPIIIURA TENERA. 



This widely-spread little creature, extending from the Mediterranean 

 on the east, to Massachusetts Bay on the west, possesses a high interest 

 as being vimparous, a fact first noticed by Professor De Quatrefages 

 (Comptes Kendus de rAcademie, XV. p. 799, 1842), and afterwards 

 more fully treated by Dr. Schultze (Miiller's Archiv., p. 37, 1852). I 

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

 of Arcachon, south of Bordeaux. They lived just below low-water-mark, 

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

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

 orange-colored young ! 



LIST OF SPECIMENS. 



Whence obtained. 



Museitm of Comparative Zoology. 



Oresund. 



Bird Isl., Bost. Harbor. 



Nahant, Mass. 



Smithsonian Institution. 



Massachusetts Bay. I 



Grand INIaiian Island. 



University Museum, 



Copenliafjen. 

 Prof. Agassiz. 

 Prof. Agassiz. 



AVm. Stimpson. 

 Wm. Stimpson. 



AmpMura tenera Lutken. 



Ampldura tenera Lutkex. Addit. ad Ilist. Oph., p. 124. 



Special Marks. — 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-papillse, to that between 

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

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

 cutting edge ; two inner ones separated, nearly equal, small, rounded, 

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

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

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

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



