7. Anthozoa (incl. Hydrocorallia). A. Zoantharia. 25 



only 4 were without an Actinian (Antholoba reticulata). Each crab bears, as 

 a rule, only 1 anemone. The anemone takes the initiative in bringing about 

 the association. 



Torrey(') regards Sagartia davisi as the Pacific representative of the S. 

 luciae of the Atlantic coast of the United States. The former does not possess 

 the yellow stripes on the column which are so characteristic of the latter. S. d. 

 is often found on the bivalve Cliione, this is not, however, a case of commeii- 

 salism. The anemone is capable of creeping more than 1 inch per hour by 

 means of processes of its pedal disc. It creeps with its long axis either bent 

 upward or at right angles to the vertical sides of an aquarium, evidently a 

 result of geotropic stimulation. Light has no effect. If a tentacle be lightly 

 touched there are usually two reactions (1) a bend at and towards the point 

 of stimulation probably due to the response of the muscles to a direct stimu- 

 lus, (2) a contraction of the whole tentacle and its bending towards the mouth. 

 Stimuli applied to the column wall produce inward motion of several or all 

 the tentacles, outward motion of a few, or the contraction of the column and 

 pedal disc according to the strength of the stimulus. Stimulation of the pedal 

 disc produces local contraction and acoutia are usually emitted, the tentacles 

 may also contract, but they do so as a whole , being unable to recognise the 

 direction of the stimulus. The responses of the tentacles to mechanical and 

 chemical stimuli are essentially the same, the bend is towards the stimulus 

 when the latter is local, towards the mouth when it is general, whether direct 

 or indirect. Chemically inert substances , if small enough to be taken easily 

 into the mouth and thus brought into contact with the ciliated cells lining 

 the stomodaiimi, are ingested, especially if the anemones be in a starved con- 

 dition. The ejection of such bodies and of food-bodies from which the 

 nutrient matters have been extracted, is due to the dominant outward beat of 

 the stomodieal cilia; these latter bodies have reached the minimum of their 

 stimulating power and are no longer able to reverse the beat of the stomodaeal 

 cilia, the inert bodies likewise cannot produce continued reversal of the cilia. 



Gary describes elongate-oval larva?, 2 to 4 mm long, covered with short 

 cilia and encircled by a ridge which bears 2 parallel bands of long stiff setae, 

 the function of which is not apparent. At the anterior and posterior ends 

 there is a depression lined with cilia, at the bottom of the former is an opening 

 which communicates with the interior of the larva. At metamorphosis the 

 larva becomes attached by the anterior end and soon afterwards tentacles and 

 a mouth are formed at the other end. Young polyps, reared in the laboratory, 

 show certain structural resemblances to mature specimens of Amophyllactis 

 which were at the same time cast upon the beach near where the larvae 

 were found. 



Carlgren( 2 ) has studied the correlation between regeneration and symmetry 

 in Sagartia viduata, in which asexual reproduction does not normally occur. 

 Longitudinal fission and laceration, especially the latter, were artificially imi- 

 tated; the longitudinal division was carried out transversely to the directive 

 plane, and cuts were made in the entocosls or exocoels so as to include pieces 

 containing the outermost part of the pedal disc and the most proximal part 

 of the body wall. In the longitudinally divided halves the margins of the 

 wound approximated after a short time, generally no new mesenteries were 

 formed and thus bilateral forms arose. Often however a zone of new growth 

 was formed along with a pair of directives and a siphonoglyph , and in one 

 case a second new stomodseurn (a double radiate form being produced). All 

 the excised small pieces produced tentacles and one stoinodyeurn or more 



