/OOUKiY FOR MEDICAL STUDENTS 



CHAP. 



.). The stomodacum is slung up to the body-wall by mesenteries 



,h<> \\in_ tin- >ame characteristics muscles (w), mesenterial filaments 



d as in the Alcyonarians but these mesenteries show charac- 



diherences in their arrangement. They are more numerous 



and are distinguishable into different sets primary mesenteries, which 



at their inner edge are attached to the wall of the stomodaeum, and others 



lary, tertiary, etc. Figs. 49 and 50, s.w) much smaller, which 

 extend imvards only a short distance and do not reach the stomodaeum. 

 Of primary mesenteries the number is from twelve upwards. They 

 an- arranged in couples and in each couple the muscular thickenings 



FIG. 50. 



lr.ui-\M-r -rations through a simple Sea-anemone (Peachia). A, Through stomodacum; 

 I'., lirlow ~t<>miUcimi. c.g, Ciliati-il groove; d, directive niescnteries ; ect, ectoderm ; end, cndodtTin : 

 : in./, iiii-i-nti Ti.il filament ; s.m, secondary mesentery ; si, stomodaeum. The mesogloea 

 i. d by a black line. 



face toward* one another, except in the case of the directive mesen- 



ilu- cnuplr which support the ventral ciliated groove and the 



couple directly opposite, which support the dorsal ciliated groove if 



one. In the case of these directives the muscles are borne not 



on tin- inner but on the outer surface, i.e. they face away from one 



another (l-'i-. 50, </). 



The ordinary sea-anemone attaches itself temporarily, the attachment 

 Mded by cement secreted by the gland-cells of its base. While as a 

 rule tlii> < ement is imperceptible it may on the other hand form a dis- 

 tinct horny layer, as happens in Adamsia, an anemone which commonly 

 vmhiotically on shells inhabited by Hermit Crabs. Finally in 

 Mil .division of the Zoantharia the secreted mass, composed of 



