92 URASTERI.K. 



" Asterias rubens molacea^ In both animal and vegetable 

 kingdoms there are genera in which we find habit of equal 

 or greater importance than minute character, in which 

 every organ and appendage are liable to variation, and 

 yet the sum of them is such as to render the recognition 

 of a species at sight easy, though it be difficult to say 

 wherefore we pronounce on its name. Doubtless this is 

 according to a fixed law as yet undiscovered ; and if 

 smaller groups and variations be analogous to the greater 

 divisions of the kingdom to which they belong, it is to be 

 expected, seeing that a fifth part of the animal kingdom, 

 according to the greater modifications of structure as in- 

 dicated by form, presents habit as a distinguishing cha- 

 racteristic. 



The Uraster molacea has the rays generally from two 

 and a half to three and a half times as long as the disk 

 is broad. They are broad at their origins, and at about 

 half their length they taper suddenly to their extremities. 

 They appear marginated, from having the upper row of 

 avenue spines placed very high, much higher than in 

 rubens. The upper surface of the rays and disk is strongly 

 reticulated and spinous, and the central ridges are very 

 regular, the spines upon them being closely set and sur- 

 rounded by spinules. They do not stop short at the disk 

 as in the last species, but meet in its centre. The spaces 

 between the reticulations are covered with pincer-shaped 

 spinules. These spinules are more pointed than the same 

 organs in Uraster rubens. Beneath, the spines bordering 

 the avenues are arranged as in the other species of the 

 genus. The avenues partake of the form of the rays, 

 being suddenly attenuate towards the extremities, very 

 wide towards their origins, and very much contracted at 

 the mouth. The form of the avenues is very constant, 





