ASTROPECTEN. 



121 



Affinities and differences. — This species very much resembles Astropecten Cotieswoldice, 

 it differs from that form, however, in having the disc smaller in proportion to the 

 diameter of the body, the rays a little swollen out in the middle, with their terminal extre- 

 mities blunt and not attenuated, as in Astropecten Cottesicoldice ; these characters may, 

 perhaps, belong to varieties of that species, for the remark already made in reference to 

 A. Cotteswoldia var. Skmfordensis, is applicable to this and other unicums, that were 

 a number of different forms of the same species before us it is possible we might be 

 able to link together differences by a series of gradations, without which the extreme 

 varieties of typical forms might be considered characteristic of different species, for it is 

 doubtless true that each species has its own limits of variation ; in some these are circum- 

 scribed, in others they are enlarged, and it is by observation alone that the boundary 

 between varieties and specific forms can be ascertained ; hence the difficulty which 

 surrounds the investigations of the palaeontologist, for his materials are m general frag- 

 mentary, in many cases unique, and always requiring the most careful study, critical 

 comparison, and accurate analysis ; so that, without inclining to Darwinian notions on 

 the one side or to modern species-making on the other, we feel the necessity of the 

 greatest caution in pronouncing on specific differences between forms of which we only 

 know solitary examples, and of these but partial details. 



Locality and 8tratigrap1nccd Position. — This Starfish was collected from the Stonesfield 

 slate of Eyeford, near Naunton, Gloucestershire, by the Rev. E. E. Witts, of Upper 

 Slaughter, to whom I have dedicated the species, as an acknowledgment of his original 

 discovery of Astropecten Cottesiooldics in the oolitic rocks of Gloucestershire. 



Astropecten Cotteswoldi.e, var. Stonesfieldenses. PI. VIII, fig. 2. 



Marginal plates thick and prominent, fifty around each ray, border straight, inter- 

 mediate angles obtuse, inter-marginal spaces of the disc and rays covered with small 

 ossicles ; the plates have become so crystalline and weathered that all their delicate 

 sculpture and other characters are effaced. 



Dimensions.- — Diameter of the body from ray point to ray point, four inches ; diameter 

 of the disc, one inch and one eighth. 



This specimen belongs to the British Museum, it was bought at the sale of the late 

 Mr. Johnson, of Bristol, and is supposed to be from the Stonesfield slate of Oxfordshire. 

 It appears to be a large example of Astropecten Cottesicoldice, but the condition of the 

 skeleton renders any minute examination thereof impossible. 



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