PEDICELLARIA. 



O. F. Mullek, in his " Zoologia Danica," was the first to point out the ex- 

 istence of certain organs in sea-urchins which have long remained a puzzle to 

 naturalists. To these organs he gave the generic name Pedicellaria, and 

 considered them as parasites of the sea-urchins. Of his genus, Pedicellaria, 

 he describes three species, which are now known to be either different stages 

 of development or different kinds of pedicellaria?, situated in various parts of 

 the shell of the sea-urchin. Our knowledge of the pedicellaria? has been 

 materially changed by the views of Delle-Chiaje, who in 1825 figured and 

 described the pedicellaria? of several sea-urchins and starfishes. He, however, 

 no longer considers them simple parasites, but says distinctly that they form 

 a part of the test of the Echinoderms, and help them in seizing their prey 

 and taking hold of adjoining bodies. Much of this view has been corrobo- 

 rated, and, like many of the shrewd observations of Delle-Chiaje, is gaining 

 only now the recognition it should have received long ago. Valentin, in 

 1841, gives in his "Anatomy of Echinus" excellent figures and descriptions 

 of pedicellaria? which he considers as organs of prehension. Agassiz at 

 that time suggested the possibility of their being young stages of Echini 

 in consequence of the discoveries just made by Sars of the remark- 

 able development of a species of starfish. This, it is needless to say, is a 

 view he has long ago abandoned, though he is most persistently credited 

 with it even at the present time. Subsequently, Erdl. Duvernoy, Muller and 

 Troschel, Sars, Stimpson, Norman, and Stewart, have figured and described a 

 number of pedicellaria? of Echini and starfishes, and have made a more or 

 less successful attempt to use their characters as aids in distinguishing closely 

 allied species. 



In an article on pedicellaria? in the " Annales des Sciences Naturelles " for 

 1869, Perrier gives a large number of excellent figures of the pedicellaria? 

 of starfishes and sea-urchins ; unfortunately the writer passes over much of 

 what has been done on the very appendages he was describing, so that 

 he leaves the question of their nature as it stood in the days of Valentin, 

 in spite of the many observations made, and hints of their true nature thrown 



