THE IRISH SEA. 117 



Sea. Six of these genera have been constituted by Agas- 

 siz, one (Solaster) indicated by Blainville, and one I have 

 thought it right to constitute, for the reception of the most 

 remarkable of all the British Asteriae, the Asterias rubens of 

 Johnston, but of no other author. The characters which may 

 be regarded as generic in the Asteriae are, 1st, The general 

 form and flatness or convexity of the surface ; 2d, The num- 

 ber of rows of suckers ; and, 3d, The structure and arrange- 

 ment of the spines, covering the surface and bordering the 

 avenues. I suspect the absence or presence of eyes will 

 also furnish a good generic character ; but, hitherto, few 

 observations have been made on those organs in this tribe. 

 It was Professor Ehrenberg who discovered that Asterias 

 violacea possesses eyes, " shewing themselves as beautiful 

 red points on the under surface of the extremities of the 

 five rays." Several of our British Asteriae have similar 

 eyes. They may easily be seen in the common cross-fish 

 or five-fingers (Stellonia rubens), and in Solaster papposa. 

 In the former, I find a very remarkable provision for their 

 protection ; each eye is placed at the extremity of the ray 

 in the middle of a circle of spines, which opens and closes 

 at the will of the animal, forming a most excellent eyelid. 

 In the Solaster papposa the eye is not so enclosed, but at 

 the end of the ray is a tuft of spines which seems capable of 

 doubling back over the eye, so as to protect it. In the 

 Goniaster Templetoni the eye is placed near the extremity 

 of the ray, apparently without any spinous protection. 

 These eyes are found in all stages of the animal's growth. 

 They are generally, but not always, preserved in dried 

 specimens ; but, as they are not visible in the dried examples 

 I possess of any other species (save the Stellonia violacea) 

 than those I have just mentioned, it is very desirable they 

 should be sought for in living individuals of the other 

 British Asteriae. 



