120 SUPPLEMENT TO GREAT OOLITE MOLLUSCA. 



and that the differences in the last volution are owing only to the stage of growth to which the specimens 

 have respectively attained. 



Index to Tab. XII, Part II, add fig8. 13, 13 a, Hinge of Corbicella. 



Page 95, fifth line from the bottom, add, and Tab. XII, figs. 13, 13 a. 



Index to Tab. XIII, fig. 16, for p. 139, read p. 140. 



Myoconcha Action, p. 77, Part II, for Tab. Ill read Tab. IV. 



Tab. XIII, fig. 18, Part II, alter dereference to, Pholas costellata, p. 142. 



Index to Part II, add, Pholas oolitica, p. 126. Tab. IX, fig. 21. 



Alaria trifida, Part I, p. 21, add the following to the description: The first two or three 

 volutions are longitudinally costated, the transverse striations extend even upon the caudal and digital 

 processes. 



Pholodomya oblita, Part II, p. 142* ; Tab. XII, fig. 5. It is now ascertained that the specimen figured 

 was erroneously assigned to the Great Oolite ; its true position is in seams of sandy marl near to the base of 

 the Inferior Oolite, in which position it occurs at various localities in the vicinity of Stroud and Nailsworth ; 

 the officers of the Ordnance Geological Survey have also procured it from a similar position in Somer- 

 setshire. It sometimes attains very large dimensions, as is exemplified by a remarkable specimen in the 

 Bristol Museum, which has been mistaken, as in other instances, for the aged condition of Pholadomya 

 fidicula, Sow. The delicate, radiating lines are scarcely distinguishable upon the aged and inflated 

 examples of P. oblita, but are always acute and conspicuous upon P.fidicula. 



Trigonia decor ata, Lye., Part II, p. 133, Tab. XV, fig. 1, alter the title to Trigonia signata, Ag., a 

 fine species, abundant in the Upper Trigonia Grit of the Inferior Oolite in the Cotteswolds, and more 

 rarely in the gray limestone of the coast of Yorkshire ; it occurs in a similar geological position at various 

 Continental localities. Professor Quenstedt has figured it from Wurtemberg under the name of Trigonia 

 clavellata. It has never been found to pass upwards into the Great Oolite. 



Patella paradoxa, Part I, p. 90, Tab. XII, fig. 2. This rare species is the Patella lata, Sow., 'Min. 

 Con.,' t. 48-1, fig. 1, p. 133. ,The compressed and imperfect specimen figured in the latter work will 

 account for our having failed at an earlier period to identify it with the very few examples which have been 

 obtained at Minchinhampton. 



Tancredia curtansata, Part II, p. 93, Tab. XIII, figs. 7, 7 a, 1 b, alter the title to Tancredia sub- 

 curtansata ; it is much less inflated, the umbones are more elevated and pointed, the posterior side is more 

 produced, and it is destitute of the large longitudinal plications which distinguish the species of the Coral 

 Rag ; the latter is also a much larger shell, only two specimens of which have come to my knowledge, the 

 type specimen in the York Museum, the other in the fine collection of Mr. Leckenby at Scarborough. 

 Tancredia Lycetti, Oppel, from the Inferior Oolite of Wurtemberg and of Gloucestershire, is also nearly 

 allied to the Coral Rag shell, and appears to be equally rare. 



Tancredia axiniformis, p. 93, Tab. XIII, fig. 6, and Tab. XII, fig. 7, alter the title to Tancredia 

 exlensa, Lye. In this instance the name proposed in my first notice of the Genus Tancredia, ' Ann. and 

 Mag. Nat. Hist.,' Dec., 1850, must be retained, as an examination of many Yorkshire specimens of 

 T. axiniformis leaves no doubt that it is a distinct species, which occurs in the Inferior Oolite, both in that 

 county and in Gloucestershire ; compared with the Great Oolite T. extensa, it is shorter, more flattened, 

 approaching more nearly to the outline of T. brevis, but with much less convexity. 



Tab. XV, Part II, figs. 2, 2 a, alter the title to Ceromya Bajociana, D'Orb. ; the figure represents the 

 usual size attained by this Ceromya in the Inferior Oolite of the Yorkshire coast ; in the Cotteswolds the 

 same formation produces it of far larger dimensions, and justifies the terms in which it is described by 

 D'Orbigny in his ' Prodrome,' p. 274, as follows : " Magnifique espece courte, renfle'e a crochets tres- 



