COMMON EGG-UttCHIN. 1 . r ). r ) 



flattened heads, giving them the appearance of so many 

 golf-clubs. To all these plates a complicated machinery of 

 muscles and ligaments is attached. The teeth themselves 

 are very long and slender, soft, and bent inwards at their 

 upper parts, hard and enamelled towards their points. 

 Their outer surface is prismatic, and grooved in the centre ; 

 their inner fluted, but having- a strong, very prominent, 

 compressed rib or keel running down to near the triangular 

 point. Dr. Sharpey remarks on them that they " are very 

 hard at the point, but softer towards the roots, where they 

 are easily separated into transverse scales or plates, with 

 a fine silky or asbestine lustre ; they seem to grow con- 

 tinually at the root, and wear at the point as in the Ro- 

 dentia." Round the inner margin of the mouth of the 

 shell are five large oblique plates of a quadrangular form 

 with a wide oval aperture in the centre. These serve for 

 the attachment of the muscles which connect the lantern 

 with the shell, and through their perforations pass the aqui- 

 ferous vessels of the avenues. 



Scattered over the surface of the body and around the 

 mouth are great numbers of PedicelZarite, bodies of the 

 same form and similar structure with those described under 

 the account of the Starfishes of the genus Uraster. These 

 were first observed on the species before us by Muller, who 

 described and figured three kinds in the Zoologia Danica. 

 They have since been investigated carefully by Sars ; and, 

 as his account, being published in the Norwegian language, 

 is inaccessible to most English readers, I shall make no 

 apology for giving a full abstract of his observations, and 

 then offer my own comments. Muller conceived them to 

 be parasitic animals, Lamarck followed him, and Cuvier 

 also, with a doubt, as also Schweigger. Munro, Oken, 

 and Sharpey regard them as organs of the animal. 



