7. Anthozoa (incl. Hydrocorallia). A. Zoantharia. 23 



from the fluids of the intervening spaces. The true nervous system consists 

 of the elements in the mesoglcea described above. If a mechanical stimulus 

 is applied to the middle of the column, in about a minute a well-marked 

 constriction encircles the animal, due to the contraction of the circular muscles 

 of the column. This occurs even when the ectoderm has been anaesthetised, 

 and the contraction is therefore probably a non-nervous direct response, com- 

 parable to those demonstrated in the muscles of some Sponges. - See also 



Pax ( 2 ). 



Annandalei 2 ) reports that the aged examples of Sagartia troglodytes described 

 by Aahworth & Annandale [s. Bericht f. 1904 Coel. p 24] are still in excellent 

 health. If a young S. happen to come into contact with the tentacles of an 

 adult, it is held for a short time only and them liberated; the mouth of the 

 adult remains closed. 



Chester finds that the method adopted by Metridium for closing a cut tentacle 

 is the same as that described by Rand [see Bericht f. 1908 Coel. p 27] for 

 other anemones. In an excised tentacle, whose tip is cut off, the distal cut 

 end becomes rounded and shows evidences of muscular contraction comparable 

 to that which produces the nipple on the attached stump, although the end 

 does not actually become nipple-shaped. The proximal end may remain open, 

 or it may close ; in the latter case deep longitudinal wrinkling is characteristic. 

 If the end of an attached tentacle, which has formed a nipple, is cut off, the 

 nipple is loosened and this end of the tentacle assumes the appearance of the 

 distal cut end of the excised tentacle described above. When the animal is 

 kept in chloretone solution until there is no response to touch, muscle action 

 being therefore eliminated, the cut tentacle does not form a nipple; the opening 

 grows smaller by means of a slow radial closure, which is completed in 10 to 

 12 hours. The nipple therefore results from muscular contraction. Polarity 

 exists in the tentacles; the effective stroke of the cilia is always towards the 

 tip, and the reaction to touch consists in contraction of a narrow circular zone 

 immediately proximal to the point of contact. Reactions in the excised tentacle 

 are similar but weaker. Inverse grafts of two tentacle fragments show no 

 reversion of ciliary action, and the reactions to touch, and the closure of cut 

 ends are the same as in similar fragments which have not been grafted. 



Carlgren( 2 ) describes the Ceriantharia collected by the Ingolf- Expedition, 

 together with other northern examples from various museums. He divides the 

 Ceriantharia into 3 families - - (1) Cerianthidse, without acontia, cnidorages 

 and botrucnidse, including (a) Pachycerianthus, in which the 2d couple of proto- 

 cnemes are short, sterile, and provided with a very well-developed cnido-glandular 

 tract; the arrangement of the metacnemes in each quartette = M, B, m, b. (M, 

 m - macrocnemes of 1st and 2d cycles; B, b - - brachycnemes of the same); 

 in one specimen of multiplicatus n. an extra mesentery had been developed 

 between the 20th and 21st mesenteries on the right side; (b) Cerianthus, in 

 which the 2d couple of protocnemes are long, fertile, and have a small cnido- 

 glandular tract; M, B, m, b; (c) Ceriantheopsis n. g. , in which the 2d couple 

 of protocnemes are long, fertile, and have a very small cnido-glandular tract; 

 m, B, M, b ; larval genera referred here Solasteractis, ? Apiactis, ? Peponactis. 

 (2) Acontiferidaa, with acontia-like threads from the craspedion [see below] 

 region on 2 or more mesenteries; Arachnanthus n. g., in which the 2d couple 

 of protocn. are comparatively short and sterile, metacn. of 1st and 2d cycles 

 without cnido-glandular tracts, but the best developed with acontia; M, B, 

 m, b; sarsi n. is possibly the adult of Arachnactis albida, on the anatomy of 

 which some notes are given; larval genera referred here - - A., Ovactis, Dacty- 



f* 



