PROM THE UPPER GREENSAND. 299 



shaped projection at the superior part of the border where the two carinas meet above 

 the vent as seen in profile in fig. 1 e. 



Affinities and Differences. — This species is well characterised by its large, deep, 

 anteal sulcus, angular upon the sides, where it is sharply defined by its two carinas, and 

 prolonged from the peristome below to the apical disc above by these boundary ridges 

 arising from the folds of the test. These characters added to the height of the test 

 with its angular circumference easily distinguish it from Cardiaster latissimus, and 

 the same group of characters readily mark it out as a very distinct form from Cardiaster 

 granulosus and C. bisulcatus. 



Locality and Stratigraphical Position. — This species has been collected only from the 

 Upper Greensand of Wiltshire ; it was formerly an abundant fossil in these beds ; but has, 

 however, now become scarce ; fine specimens with the test in good preservation are 

 seldom found. The large shells I have figured belonged to Mr. Cannington's collection, 

 and were collected many years ago. These grand specimens now belong to the British 

 Museum. 



Cardiaster Perezii, Sismonda, 1843. PI. LXVIII, fig. 2 a, b, c. 



Holaster Perezii, Sismonda. Sugli Ech. Foss. di Nizza, p. 11, pi. i, figs. 1 — 3, 



1843. 



— — Agassiz and Desor. Catalogue Raisonne des Echinides, 



p. 135, 1847. 



— — Albin Gras. Oursins Fossiles de l'lsere, p. 62, 1848. 



— bisulcatus, Albin Gras. Oursins Fossiles de l'lsere, p. 62, pi. iv, figs. 7, 



8, 1848. 



— Perezii, d'Orbigny. Prodrome, t. ii, p. 141, 1850. 



— — d'Orbigng. Paleont. Francaise Ter. Cret., p. 86, pi. dcccxiii 



figs. 1—7, 1853. 

 Cardiaster bisulcatus, Forbes. Mem. Geol. Surv., decade iv, pi. ix, Notes on 



Cardiasters, 1852. 

 — — Morris. Catalogue of British Fossils, 2nd ed., p. 73, 1854. 



Holaster Perezii, De Loriol. Echinid. Helvetique Ter. Cret., p. 325, pi. xxvii, 



figs. 6—8. 1873. 



Diagnosis. — Test convex, enlarged before, contracted behind, elevated anteriorly to 

 the ambulacral summit, and gradually inclined from thence to the posterior border, 

 anteal sulcus short, deeply indenting the anterior border, antero-lateral ambulacral 

 narrowly lanceolate ; postero-lateral ambulacra short and wide ; posterior border 

 accuminated and oblique, vent low down in a small truncated area, periprocte oval. 

 Primary tubercles very small in proportion to the size of the test, a dorsal carina 

 extending from the vertex to the border; apical disc small, situate at the junction of the 

 anterior, with the middle third of the upper surface. 



