ASTERIAS. 93 



Thus, the position of the ovarium, or rather of the ovaria, for all 

 have more than one, is determined by the species. 



In the Asterias glacialis and ruhens, they occupy a large portion 

 of the five rays, each ovarium of the latter growing to a great size : 

 those of Aderias aranciaca belong to the origin of the rays next the 

 disc, and are of quite different formation. The roe of the Solaster pappom 

 is found in the margin of the disc, of different arrangement from that of 

 the others. The roe of some Ophiarce occupies five external sacs, each in- 

 terposed between the roots of two rays, and shew, by tlieir swelling, 

 the progressive advances of their contents. 



The ova of the Astefias glacialis and riileiis seem to be discharged 

 from the end of May throughout June. On dissecting numbers of each. 

 in the beginning of July, the rays of many were entu'ely vacant of spawn. 

 But, in one large specimen of the former, a lobe of clear spawn, an inch 

 long, was found ; and in others, very small portions, which, early in the 

 season would have been considered originating lobes in both. 



The rays are now distended by water. 



The embryo animal, originally cii'cular, is gradually moulded into 

 form, when Uberated from the capsule : the limbs are successively de- 

 veloped from the margin, the whole meanwhile presenting an irregular 

 distorted aspect until attaining syiinuetry. 



The young animals seldom occur at large in a A^ery early stage. \A'lien 

 they do so they are preserved without difficulty. 



The Star-fish evidently live many years. Some are extremely com- 

 mon, others are of great rarity. 



The history of the Star-fish may be divided into two sections — 

 I. The Aaterias — II. The Ophiura. 



Section I. — § 1. Asterias Glacialis. — Northern Sea-star, Cross-fish. — - 

 Plate XVI. 



This animal seems to be generally and numerously dispersed through- 

 out the northern regions. It is abundant in the Scotish seas, insomuch 

 that description Is hardly essential, for none other is the subject of inci- 

 dental reference. 



