XIV.—On the Histology of the Pedicellariæ and the Muscles of Echinus sphæra (Forbes)

Extract

The structures known as pedicellariæ were first described by O. F. Müller. He regarded them as parasitic organisms, and described under the generic name of Pedicellaria three species—Pedicellaria tridens, P. triphylla, and P. globifera. Lamarck, in the first edition of his “Animaux sans Vertèbres,” published in 1801, and also in the second edition, following Müller, classified the genus Pedicellaria with the Corynidæ and Hydridæ among the naked polyps. Cuvier also, in the first edition of the “Regne Animal,” took the same view of the nature of pedicellariæ. It was not until 1825 that the real nature of these organs was recognised. Delle Chiaje, in his work on invertebrate animals, asserted that pedicellariæ formed an integral portion of the Echinus, and were simply appendages of the test. The following quotation from his work shows that he thoroughly understood the true nature of these structures. He says (vol. ii. p. 324):—“Fanno elleno parte integrale degli echini e servon loro per attacarsi a corpi adiacenti ed anche a ritenere gli animaletti da cibarsi.”