96 ECHINODERMATA. 



After sumdving six or seven months, this specimen perished acci- 

 dentally. 



During the season of propagation, the rays of the Aster ias glacialis 

 are distended by a great ovarium. This, perhaps, may be considered as 

 divided into five parts, one occupying each ray ; each part, consisting 

 of two triangular lobes of unequal size in CA^ery ray, ■with subordinate 

 parts, also triangular, and resembUng clusters of currants or grapes. To- 

 wards the end of May they are seen to be an accumulation of speckled 

 capsules, which burstuig, discharge a quantity of molecules, like dust, 

 falling to the bottom of the vessel. — Fig. 6. 



The capsules farthest advanced belong to the larger portion of the 

 roe, that towards the hodij of the animal which seems the first to origi- 

 nate. A solid nucleus within an integument is discovered in each of the 

 molecules discharged from the capsule. The spawn is long of attaining 

 maturity ; the lobes represented, fig. 6, being only in progress in the 

 end of April. A month, or perhaps two, had still to elapse before the 

 discharge of the ova. — Fig. 7. 



This species is extremely subject to mutilation of the rays. It is 

 constantly found with one or more in progress of reproduction. Muti- 

 lation does not seem incidental to age, size, or season. But to shun re- 

 petition, I shall reserve a few observations on the subject for the follow- 

 ing paragraph. 



I am igiiorant whether specimens, originall}' white, invariably 

 change their colour, having witnessed its permanence in some of con- 

 siderable size, as pre^douslj- said, 



Plate XVI. 



Fig. 1. A sterlas glacialis — The Northern Sea-star, adult. 



2. Young specimen. 



3. Young specimen, originally white. 



4. Ray of fig. 3, enlarged. 



5. Fig. 3 represented four months later than previously, being now- 



purple. 



6. Lobes of spawn. 



7. Ova enlarged. 



