W. R. Hudleston—The YorUMre Oolite. 125 



The aperture is irregularly quadrate: angular externally, and but 

 little cut away on the interior. 



Relations and Distribution. — This is by far the finest specimen of 

 the ornamented group of Pleurotomuria, allied to PI. anglica, which 

 has ever been found in beds of this age in Yorkshire. There is a 

 specimen in the Leckenby Collection — length 32mm., width 28mm. 

 — which may be regarded as representing the usual size of this some- 

 what rare form. Thus Sir Charles Strickland's shell may almost be 

 viewed as a megalomorph, bigger even than the foreign sj^ecimens 

 described by Goldfuss and D'Orbigny. It is only right to point out 

 that D'Orbigny describes Fl. Agassizii as having the aperture 

 shortened anteriorly, which can hardly be said to be the case with 

 this shell, whose aperture is more like that of PL Mesione, D'Orb., or 

 of PI. Pha'dra, D'Orb., which are supposed to represent this group 

 on a higher horizon. 



D'Orbigny's PI. Agassizii has been obtained in the Yonne, Haute 

 Saone, and Charente Inferieure. In the Corallian of Weymouth there 

 is a shell which has more affinity with PL Pelea (see Damon's 

 Suppl. 1880, pi. xvii. fig 8), having only a single instead of a 

 double row of tuberculations, and being in other respects diffei'ent 

 to the North Grimston shell. Whiteaves (Ann. and Mag. Nat. Hist. 

 1861, vol. viii. p. 142 et. seq.) quotes a new species of Pleurotomaria 

 allied to anglica from the Corallian of Oxford, and somewhat similar 

 forms have been found sparingly in the Coral Eag of other districts. 

 Genus Patella, Linnseus, n58=zIIelcion, Montfort and D'Orbigny. 



Shells of this genus are particularly scarce from the Corallian 

 rocks of Yorkshire. There are one or two bad specimens in some 

 collections, but the only decently-preserved specimen known to me 

 is the one described below. 



54. — Patella kugosa, Sowerby, 1816. Variety. Plate lY. Fig 5. 

 Fatella rucjosa, Sowerby, 1816, Min. Conch, t. 139, fig. 6. 



Idem. Idem. 1850, Morris and Lycett, Gt. Ool. Moll. p. 89, pi. sii. figs. 



1, \a-g. 

 Fatella Ifosensis, Buvignier, 1852, Stat. geol. de la Mense, p. 27, pi. 21, figs. 3-4. 



Bibliography, etc. — The type form of Sowerby's species is the well- 

 known and abundant Patella from Minchinhampton, of which such 

 forms as P. Tessoni, Deslong., may probably be regarded as megalo- 

 morphs. With modifications, P. rugosa would seem to have an 

 extensive vertical range. Helcion Pupellensis, D'Orb. (Prod, de 

 Pal. Strat. vol. ii. p. 12), from the Corallian of La Eochelle, is 

 probably a representative. P. Mosensis, Buv., is also a near relative, 

 representing the species on the same horizon in the region of the 

 Meuse. That author describes his species as being near to P. rtigosa, 

 Sow., from which it is to be distinguished by a sharper apex, finer 

 lines of increase, and less elevation. Buvignier's figure, however, 

 will hardly fit the Yorkshire specimen. 



Description. — Specimen from the Coral Eag of North Grimston 

 (Strickland Collection). 



Length 25 millimetres. 



Width 21-5 



Height ? 8 



