ARCHAEOCIDARIS. 277 



Cidaris vdttsfa Phillips, 1836, p. 208; Portlock, 1843, pp. xxvi, 353, Plate 16, fig. 11. 



Echinocrinus urii L. Agassiz, 1841, p. 16; M'Coy, 1844, p. 174, Plate 27, fig. 1 (the generic name on legend 



of plate in pencil).' 

 Cidaris hrnhurhcnsis Portlock, 1843, pp. xxvi, 352, Plate 16, figs. lUa-lOd. 

 Echinocrinu.s irtustus M'Coy, 1844, p. 174. 

 Archacocidaris urii Roemer, 1852-54, p. 288, Plate 4, fig. 2; Desor, 1858, p. 154, Plate 21, figs. 11, 12; 



Baily, 1875, p. Ixviii, Plate 36, figs. 12a, 12b; Keeping, 1876, p. 39, Plate 3, figs. 14-18; Julien, 1896, 



p. 123, Plate 16, figs. 8-10; Tomquist, 1897, p. 775, Plate 22, figs. 4-7, 11; Fraipont, 1904, p. 11, 



Plate 1, fig. 5; Lambert and Thiery, 1910, p. 124. 

 Arrharoridaris vriustu Dujardin and Hupe, 1862, p. 466; Lambert and Thiery, 1910, p. 124. 

 Archacocidaris [urii] Young, 1873; 1876. 



Archacocidaris urci Loven, 1874, p. 43; Neilson, 1895, p. 77, text-fig. 3; Klem, 1904, p. 59. 

 Archacocidaris benburhensis Etheridge, 1888, p. 221. 

 Archaeocidaris gruncri Julien, 1896, p. 125, Plate 16, figs. 11, 12; Klem, 1904, p. 62; Lambert and Thiery, 



1910, p. 124. 

 Archacocidaris rcgimontana Parkinson, 1903, p. 365, Plate 15, fig. 13; Lambert and Thiery, 1910, p. 124. 

 Archacocidaris vctustus Klem, 1904, p. 61. 



This species is widely distributed and represented by some very good material. The 

 most complete portion of a test known to me is from Knock Hill Quarry, Fife, Scotland, and 

 is in the Museum of Practical Geology, London. In this specimen (Plate 15, fig. 1) the ambu- 

 lacrum is narrow, 5.5 mm. in width. The ambulacral plates are low with pore-pairs uniserial. 

 In one area of this specimen it is seen that there are four columns of interambulacral plates, 

 the same number that is found in all other species of the genus where a complete area is known. 

 The interambulacral plates of median columns are low, wide hexagons, and those of adradial 

 columns are pentagonal with a strongly rounded line on the adradial suture. This specimen 

 shows that there are four plates in the basicoronal row of the interambulacrum and also traces 

 of ambulacral and non-ambulacral plates on the peristome (compare Plate 9, figs. 6, 7). The 

 largest interambulacral plate measured is 12 mm. in width by 6.5 mm. in height. The surface 

 characters of the plates are not shown well in this specimen, though they are in others from the 

 same locality. In another specimen from this locality in the Jermyn St. Museum, an interam- 

 bulacral plate measures 13 mm. in width by 9 mm. in height. It also shows primary spines 

 of the usua,l size and character in the species. 



' In a copy of M'Coy's Carboniferous Limestone Fossils of Ireland, of the 1S62 edition, seen at the Jermyn St. Museum, 

 London, the name Cidaris urii is printed on the plate as stated (p. 276). In two copies of the 1844 edition, which was 

 privately issued by Sir Richard Griffith, one at the British Museum, and one at the Musemn of Comparative Zoology, the 

 generic name is erased on the plate and changed in jiencil to read Echinocrinus urii. Dr. Bather (1907, p. 453, footnote) 

 says of M'Coy's publication, "In the legend to the lithographed plates the name Archaeocidaris, which had been printed, 

 was erased, and the name Echinocrinus inserted by hand." According to the evidence Dr. Bather is mistaken, and the 

 name erased was doubtless Cidaris, not Archaeocidaris. (See footnotes, pp. 275, 280.) 



