ASTERIAS. 117 



§ 2. Ophittra vulgaris. — Plate XXVIII. 



This is the most common, and its varieties the most numerous, of 

 any that I have seen, insomuch, that it is somewhat perjDlexing to say 

 what shall be assumed as the tj'pe of the species. 



The profusion and the distribution of colours in every different pro- 

 portion, distinguishes it among the rest, for yellow, blue, green, red, may 

 be interspersed in a single sijecimen : — Plate XXVIII. fig. 1. Three lines 

 in length — ^being a portion of the five raj's of one specimen, were of uni- 

 form yellow from their origin, when the interspersion of other colours 

 commenced. 



The finest specimens, which are found in the northern seas of Scot- 

 land, expand six inches between the tips of the opposite rays. 



The proportion of the disc to the whole dimensions of the animal is 

 small ; but the form and appearance not only undergo great modification 

 in attaining the adult state, but during the season of propagation these 

 are still more conspicuous. 



Early in the season ovoids begin to swell from the margin of the 

 disc between the rays. Advancing gTaduaUy through March and Apiil, 

 they become so much enlarged in May and June, that the rays inter- 

 posed between them seem reduced m size, and as if grown more slender. 



The ovoids, when mature, are full of a number of thin brownish or 

 yellowish foliaceous lobes, composed of a vast multitude of ova. 



The rays of this species are particularly subject to mutilation. 



They are clothed by sets of hard and soft processes, adapted to va- 

 rious purposes. 



Plate XXVIII. 



Fig. 1. Oph'mra vulgaris. 



2. Section of a ray, enlarged. 



3. Section of a ray. 



4. Cartilaginous organ of tlie ray. 



5. Spinous organ of the ray. 



6. Disc of a prolific specimen, surface. 



7. The same, under surface. 



8. Disc of a specimen, enlarged. 



9. Foliaceous lobe, from an ovoid, enlarged. 



