86 ECHINODERMATA. 



part corresponding in position with the head of other animals, and all 

 the tentacular organization or arborescence may be withdrawn, and, 

 after an indefinite period of concealment, again displaj-ed at will. 



III. The arborescence is always retracted during alarm, nor ever 

 displayed unless under a sense of security. 



IV. The Holothuria pentodes, fu$us, and phantapus, propagate by 

 ova, and probably most of the others, the ovarium consisting of the ova 

 disposed in long ropes, single or folded double, and hi vast profusion. 



V. The Holothuria Bodotrice multiplies by spontaneous division of 

 the body, and subdivision of the sundered parts. 



VI. Some of the Holothuriae, as the fusm, are subject to lose the 

 tentacula, cylinder and ovarium, together with a large proportion of the 

 intestines, by spontaneous extrusion, the whole of which will be repro- 

 duced through time and favourable circumstances. 



VII. Most of the tribe, if not the whole, and especially the 

 pentactes, are liable to rupture of different parts of the body in confine- 

 ment, the rupture always proving fatal if near the posterior extremity. 



VIII. All the Scotish Holothuriae dwell under the surface of the 

 sea in the natural state, and firmly affixed for the most part to solid 

 substances. 



IX. The Holothuria is apparently a nocturnal animal, the full de- 

 velopment of its organs, and the discharge of its more important func- 

 tions, being chiefly during the night. 



X. Little Is known regarding the general habits of the Holothuria 

 in its native state. All seem of extreme timidity, disposed to shun the 

 light, and remain quiescent during the day. The pentactes generally 

 rises near the surface of the water, thefmus is content to remain below. 

 Both adopt a crescent shape, which is also the nature of the Holothuria 

 Scotica. The Holothuria Bodotrice or Ocnus does not affect any particular 

 position, and often remains very long affixed to the same spot. 



Perusal of the first part of the Professor Delle Chiaie's Instituzioni di 

 Anatomiae Fisiologia Comparata, Napoli, 183G, and of Professor Edward 

 Forbes' Treatise on the Echinodermata, 1841, will much facilitate the 

 student's knowledge of these remarkable animals. 



