On a Spine from the Coal-measures of Northumberland. 217 



In each of the above particulars the specimens in question 

 accord exactly with the diagnosis given by the eminent Nor- 

 wegian naturalist. Specifically, however, Pedicellaster palceo- 

 crystallus, nobis (for such it should accordingly be written), 

 differs unequivocally from P. typicus, Sars (the only repre- 

 sentative of the genus hitherto known), in the general size, 

 proportions, and habitus of the starfish, as well as in the form 

 of the pedicellaria? and spinelets. P. palceocrystallus is of 

 larger size; and the length of the arm-radius in proportion to 

 that of the disk (about 5:1) is less than in P. typicus, in 

 which it is 6h or 6 : 1 ; the contour of the arms is also diffe- 

 rent in our form, being more tumid on the inner third and 

 much more attenuated on the remaining outward portion of 

 the ray ; the dorsal spinelets are decidedly radio-laminate and 

 somewhat expanded at the tip, instead of being conical as 

 described in P. typicus ; and the shaft of the ambulacral spine- 

 let is denticulate ; whilst the pedicellarire in the present species 

 differ in being of even larger size and having the contour of 

 the jaws considerably swollen out about the outer third and 

 then tapering rapidly towards the extremity, which is some- 

 what truncate. 



Other minor differences occur ; and these, together with 

 figures, will be recorded in the memoir on Arctic Echino- 

 dermata, in course of preparation by Prof. P. Martin Duncan 

 and the writer. 



The great rarity of the genus Pedicellaster and the interest 

 attaching to its occurrence in such high latitudes may be urged 

 in justification of the present advance-note upon the subject. 



XX. — On a Spine (Lophacanthus Taylori, rnihi, nov. gen. 

 et spec.) from the Coal-measures of Northumberland. By 

 Thomas Stock, of the Natural-History Department, 

 Museum of Science and Art, Edinburgh*. 



Amongst a parcel of fish-remains sent me a few months ago 

 by Mr. Joseph Taylor of Shire Moor, Northumberland, was 

 a spine which Mr. Taylor said he believed was new. After 

 a careful study of the specimen, and after consulting all the 

 literature of the subject accessible to me, I came to the conclu- 

 sion that the spine was not only specifically new, but must 

 be regarded as the type of a new genus. 



Description. The spine, as I received it, was in three frag- 

 ments : the two upper were partially imbedded in the matrix ; 



* Read befoiv the Edinburgh Geological Society, Dee-ciuber 1879. 



