4138 Radiata. 



by Mr. Forbes as being not uncommon in specimens obtained from 

 the Irish Sea, (p. 52). 



Ophiocoma bellis. Under "specific character" of this species, 

 Mr. Forbes describes the disk as " subpentangular," and the same is 

 repeated in his text. In three out of eight of the many examples that 

 have come under my observation, the reverse is the case, the greater 

 number being round, or as nearly so as may be imagined. I would 

 also say that the sides are less tumid than one would infer is intended 

 by his description, and all are more thickly set with plates than 

 is shown in his figure. In size, the disks vary from three-fourths to 

 one-tenth of an inch in diameter, and in the case of one the surface 

 is strongly hirsute. I have "found them under stones at very 

 low tides," but have also known them drawn from water of considerable 

 depth along with Thuiaria thuia. A more intimate and extensive ac- 

 quaintance with this species induces me to question whether the indi- 

 vidual described and figured in the ' Zoologist' for 1850, under the 

 name of Ophiocoma parmularia, be after all a distinct species, and not 

 rather a variety of the present one ? It certainly appears to differ 

 from the description of Mr. Forbes in all the particulars so minutely 

 stated by our late lamented and esteemed friend the Rev. James 

 Smith, of Monquhitter. Yet, apart from the wedge-shaped scales at 

 the insertion of each ray, the chief distinctions or disparities being 

 the form, number of plates, and the arrangement or rather number of 

 spinules, these variations cannot, I consider, be said to be greater 

 than are frequently found to exist between identical individuals 

 of other species, particularly where the comparison has been insti- 

 tuted on examples gathered from localities widely apart ; and though 

 the scales at the origin of the rays certainly present, to the eye as well 

 as under a lens, a wedge-shaped appearance in their general outline, 

 which is owing obviously in part to colour, or perhaps more properly 

 to the want of it, it is possible that, were the specimen broken up and 

 carefully dissected, it might be found to have little if anything more 

 peculiar in it, than could be accounted for by the fact of its being 

 more numerously covered with plates, while at the same time less 

 thickly set with spinules than is usual. To my mind, by far the most 

 important feature lies in these wedge-shaped scales, and were this 

 authoritatively ascertained, I should have no hesitation in regard to a 

 distinction of species; but more extended opportunities of examining 

 these genera satisfy me that a wider range of variation falls to 

 be admitted in the identification of species, than can reasonably 

 be claimed in the classification of most other forms of animal life. 



