382 CLYPEUS 



Clypeus subulatus, Young and Bird. PI. XXXIV, fig. 1 a, h, c, d, e,f,g. 



EcHiNiTES SUBULATUS. Young and Bird, Geol, Surv. of the Yorkshire Coast, pi. vi, 



fig. 11, p. 214, 1827. 

 Clypeus emarginatus. Phillips, Geology of Yorkshire, pi. iii, fig. 18, p. 127, 1829. 



— — Morris's Catalogue of British Fossils, p. 50, 1843. 



NucLEOLiTES EMAEGiNATUS. Forbes, Memoirs of the Geological Survey, Decade 1, 



descrip. pi. i. 

 — — Wright, Ann. and Mag. of Nat. Hist., 2d ser. vol. ix, p. 310, 



1851. 

 Pygukus emarginatus. Desor, Synopses des Echinides Fossiles, p. 316, 1857. 



Test large, oblong, and much depressed ; sides equally declining ; vertex and apical 

 disc nearly central; ambulacra narrowly lanceolate; poriferous zones petalloid, on the 

 upper three fourths of the dorsal surface; simple, in the lower fourth; anal valley 

 short and deep, far removed from the disc, and occupying the lower third of the area ; 

 anterior border rounded ; posterior border produced, rostrated, and deflected ; base con- 

 cave ; mouth subcentral ; basal inter-ambulacra much cushioned ; margin gently undulated ; 

 tubercles small, and disposed in rows. 



Dimensions. — Large specimen, fig. 1 a, b. Height, one inch; antero-posterior 

 diameter, three inches and four tenths ; transverse diameter, three inches and one fifth. 

 Smaller specimen, fig. 1 c, d. Height, nine tenths of an inch ; antero-posterior diameter, 

 two inches and six tenths ; transverse diameter, two inches and six tenths. 



Description. — This beautiful Clypeus has hitherto been found only in the Coralline 

 Oolite of Yorkshire, and was first described from that formation by the Rev. George 

 Young, in his ' Survey of the Yorkshire Coast.' The figure given in that work is very bad, 

 but the description is sufficiently accurate to identify the species : " The dorsal surface 

 has the same elegant markings as No. 5 {Py gurus pentagonalis), but the petals are rather 

 awl-shaped than lanceolate, from which peculiarity we name it EcJnnites suhulatus. The 

 middle part of each petal forms a slight ridge ; on the contrary the five corresponding 

 marks on the base, meeting in the mouth, are depressed. The base is concave, and the 

 mouth is situated immediately under the vertex. The vent is in a short groove on the 

 edge, but more towards the upper surface, as in some of the Spatangus family."* 



When I published my memoir on the Cassidulidae of the Oolites f I could not obtain a 

 specimen of this urchin ; most of those contained in the Yorkshire collections are either 



* Geological Survey of the Yorkshire Coast, 2d ed. p. 214. 



t Annals and Magazine of Natural History, 2d series, vol. i.x, p. 310, 1851. 



