334 ECHINOBRISSUS 



Dimensions. — Large Cornbrash specimen (fig. 1 h). Height, eighteen twentieths of an 

 inch ; anterior posterior diameter, one inch and thirteen twentieths ; length from the 

 border to the posterior sulcus, one inch and eleven twentieths ; breadth across the apical 

 disc, one inch and eight twentieths. 



Cornbrash specimen (fig. 1 a). — Height, eight tenths of an inch ; antero-posterior 

 diameter, one inch and one quarter of an inch ; transverse diameter, one inch and one 

 quarter of an inch. 



Inferior Oolite specimen. — Height, six tenths of an inch ; antero-posterior diameter, 

 one inch and three tenths of an inch ; transverse diameter, one inch and three tenths of an 

 inch. 



Description. — This is doubtless the urchin to which Llhwyd* gave the name Echinites 

 clunicularis, and described " Echinites e lapide selenite, quinis radiis e duplice serie trans- 

 versarum lineolarum conflatis," he refers to the figures in Plott f and Lister, ^ but as these 

 exhibit no anal valley, it is impossible to say whether they represent this species or the 

 Coral Rag form. The figure given by Breynius,§ and described as Echinobrissus planior, 

 represents this species as shown by the length of the anal valley, which reaches as high as 

 the disc, whilst Echinobrissus elateor, fig. 3 of the same plate, represents E. scutatus from 

 the Coral Rag. This most acute observer had therefore clearly distinguished and figured 

 a diagnostic specific character which has been overlooked by subsequent authors, and led 

 to much confusion in the synonyms of E. clunicularis. Spatangus depressus, of Leske, || 

 most probably represents a large quadrate variety of E. scutatus, and is consequently 

 omitted from our list of synonyms. Dr. William Smithy figured in his plate of charac- 

 teristic Coral Rag fossils an urchin to which he gave no name. This Fleming** refers to 

 E. clunicularis, whilst he calls E. lobatus the species figured by Lister, forgetting that 

 Llhwyd referred to Lister's figure as the type of E. clunicularis. Professor PhiUipsff 

 distinguishes the two species from each other, and restricts the name E. clunicularis to the 

 Cornbrash form, whilst he figures the Coral Rag nucleoli te as E. dimidiatus. Continental 

 authors have made several species out of the simple varieties of E. clunicularis ; but when 

 we recollect the many varieties of figure and outhne which this urchin exhibits, any 

 erroneous multiplication of species is readily explained. 



Professor Edward Forbes f :|: considered E. scutatus, Lamk., a variety of E. clunicularis. 

 This error, however, he afterwards corrected, when he became acquainted with the true 



* • Lithophylacii Britannici Ichnographia,' p. 48, No. 988. 



t 'History of Oxfordshire,' table ii, fig. 12, 1698. 



X ' De Lapidibus Turbinatis,' cap. 11, titulus xxvi, 1678. 



§ ' Schediasma de Echinis,' tab. vi, figs. 1, 2. 



II 'Dispositio Naturales de Echinodermatuni,' tab. li, figs. 1, 2. 



^ ' Strata Identified by Organized Fossils.' 

 ** ' British Animals.' 

 ft ' Geology of the Yorkshire Coast.' 

 XX * Memoirs of the Geological Survey,' decade i, pi. ix. 



