456 GENERAL CHARACTERS OF STAR-FISH. 



apparatus (by which water is introduced into the body from 

 without) seems to be the principal means of respiration enjoyed 

 by the animal. The ovaria are disposed in a radiated form 

 around the mouth; and they are found to be turgid in the spring 

 and the commencement of the summer. Their spawn is thrown 

 out upon sandy shores, where it is exposed to the action of the 

 sun. It has not, however, been properly examined ; nor has the 

 mode of development of the young Star-fish been studied. 



1013. The mouth of the Asterice opens at once into the 

 stomach ; it is unprovided with teeth ; and the digestive secre- 

 tions appear to constitute the only means possessed by the 

 animal of reducing its food. There is considerable variety in 

 this group, as to the number of rays, the proportion which they 

 bear to the central disk, and the degree in which the stomach 

 is continued into them. Some are so little divided at the 

 edges, that in external form they approach the Clypeasters 

 ( 1011) ; whilst in others the disk seems almost absent, the 

 animal being, as it were, all rays. In general organisation, 

 however, there is a pretty close correspondence throughout. 

 The Asterice appear to enjoy a considerable amount of loco- 

 motive power. Their rays are very flexible, so that they 

 can be drawn up towards the mouth, or moved from side to side 

 towards each other, so as to give the animal the power of insi- 

 nuating itself through narrow apertures. The rays appear to be 

 principally moved by the general integument, which is thick and 

 contractile. Small red points have been observed at their 

 extremities in some species, which, from their connection with 

 the nervous cord of each ray, and from their analogy with the 

 eyes of other Invertebrata, are believed to be visual organs. 

 This belief is strengthened by the observation of Professor 

 Forbes, that the spines are disposed around them in a peculiar 

 circular mode, so that they may be closed over these organs 

 for their protection, or may diverge for their most extended 

 employment. The same gentleman has remarked that these 

 animals appear to take cognisance of objects of food placed at a 

 little distance from them ; and that, in their movements from 

 place to place, they seem to be aware of obstacles in their direct 



