THE COASTS OF SICILY. 179 



coming forth only for a moment into the pure light of 

 the sky, and then, at the least indication of danger, 

 boundino; with a vio-orous stroke of their tail back 

 to the shelter of their sombre retreats. Amongst 

 these animals, whose forms were more or less familiar 

 to us, were other species, belonging to types wliich 

 rarely or never reach our northern latitudes. There 

 was the Comatula*, a near ally of the Asteridae, and 

 which, to a certain extent, represents in existing 

 creation the Crinoidae, which, although nearly extinct 

 in our own day, are very common in a fossil state. f 

 There were strings of crystal-clear Salpas, paradoxical 

 molluscs, which are alternately oviparous and vivipa- 

 rous, and whose successive generations are alternately 



* The Comatula is an Echinoderm, whose arms, instead of being 

 simple like those of the Ophiura, or ramified like those of the 

 Euryale, are furnished with a double series of pinnae, which give 

 them the appearance of the leafy stems of certain plants. The 

 organisation of the Comatulas has been studied by several natu- 

 ralists, and amongst others by M. Dujardin. 



f The Crinoids, Stone Lilies, or Encrinites (Encrinus), form a re- 

 markable group among the Echinoderms. Their body resembles in 

 many respects that of the Comatula, but instead of being free like the 

 latter, the Encrinites are affixed to the extremity of a long peduncle, 

 which is itself composed of solid pieces, which are articulated, or, 

 more correctly speaking, superposed upon one another and con- 

 nected by soft parts. These small discs often exhibit the form of a 

 star, composed of five regularly arranged points. The Encrinites 

 constitute one of our commonest forms of fossils, and it was long 

 supposed that the type had entirely disappeared from our existing 

 Fauna, but in the last century the Academician Guettard discovered 

 in the collection of M. Boisjourdain, a specimen of a living Encrinite 

 which he described, and which is now in the Museum. Living 

 Encrinites are, however, of very rare occurrence near our shores, 

 although they are said to be very common in the seas washing the 

 coast of Florida and the island of Barbadoes. 

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