394 S. J. HOLMES 



in food taking. The differences in the behavior of the two 

 species are considered to be largely responsible for their differ- 

 ences in habitat. 



Carpenter ^^ has shown that when meat or solid food is placed 

 on the disk of the rose coral the disk is drawn down, and the 

 margin of the oral surface folded over, thus improvising a sort 

 of digestive cavity. At the same time the stomodeum is everted 

 and the mesenterial filaments extruded through the mouth, 

 and digestion takes place in the space formed by this invagi- 

 nation. The cilia of the tentacles beat outward as in many 

 other anemones and serve to rid the disk of foreign bodies, 

 but occasionally in response to food stimuli the direction of 

 the ciliary beat is reversed. There is a transmission of impulses 

 from the ectoderm through the mesogloea to the entodermic 

 muscles, but the histological basis for this transmission is at 

 present not satisfactorily determined. 



The object of Cowles's ^* study was to determine whether 

 it is the direction of the rays or the relative intensity of the light 

 that controls the direction of movement in the starfish. Light 

 was admitted through a prism of India ink, in such a way that 

 it gave a field of graded intensity in the aquarium below, in 

 which the starfish were confined. It was shown that the star- 

 fish uniformly moved from the darker to the lighter end of 

 the aquarium, regardless of whether they moved with or against 

 the direction of the rays. A specimen with the tips of the rays 

 amputated reacted in the same way, but much more sluggishly. 



Cowles ^^ gives a general account of the normal behavior of 

 several species of ophiurans. Normal locomotion, the role 

 of the tube feet in locomotion and feeding, and the righting 

 movements are described in detail. The direction of righting 

 is influenced by light, contact, and the previous handling of 

 .certain rays. The ophiurans react negatively to light and show 

 a tendency to approach dark walls. 



While the greater part of Dakin's =** paper deals with the 

 structure and connections of the visceral ganglion, there are 

 included a number of interesting observations on behavior. 

 Pecten is capable of rapid swimming by the alternate opening 

 and closing of the valves of the shell. It may be induced to 

 swim by various kinds of stimuli, but it is particularly sen- 

 sitive to the presence of a starfish. It does not recognize 



