16 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. |~Ap r - ®> 



Quenstedtia laevigata, Phil. sp. 



? tenuissima, Bean, MS. 



Tancredia axiniforrnis, Phil. sp. 

 Mya ? sequata, Phil. 

 Corbula dubiosa, Bean. 

 Thracia, sp. nov. 

 G-oniomya angulifera, Sow. sp. 

 Ceronrya Bajociana, d'Orb. 

 Gresslya abducta, Phil. sp. 

 Sowerbya triangularis, Phil. sp. 



Cardium crenulatum, Bean, MS. 

 Trigonia costata *, var. pullus, Sow. 



V-eostata, Lye. 



composita, Lye. 



Opis Phillipsii, Morris. 

 Astarte elegans, Sow. 



excavata, Sow. 



minima, Phil. 



Isocardia cordata, Buckm. 

 Cytherasa dolabra, Phil. 

 plana, Bean, MS. 



No. 2. This very richly fossiliferons seam is made up of a con- 

 geries of shells, which lie in all directions in the hed. Chem- 

 nitzia and Nerincea are found ahove ; and JSfatica, Astarte, and Tri- 

 gonia are in great abundance beneath. The matrix is deeply impreg- 

 nated with ferruginous matter. The shelly conglomerate is ex- 

 tremely hard, of a deep-brown colour, and forms a conspicuous 

 band, about one foot in thickness, in the cliff. It rests upon a 

 second unfossiliferous sand-rock, similar to the upper sandstone, 

 the fossiliferous seam being interstratified between them. 



No. 3. Beneath the preceding is another sandstone, charged with 

 iron, but with few or no fossils, and measuring from six to eight 

 feet in thickness. The three beds may be considered as one ferru- 

 ginous sandy deposit, with an intermediate fossiliferous zone. The 

 whole measures from 16 to 18 feet. 



* [This valuable note has been contributed by John Lycett, Esq.] Trigonia 

 composita, Lye. (Syn. Trigonia striata, Phillips, Geol. of Yorksh. vol. i. pi. 1 1 . 

 fig. 38., not T. striata, Sow.). This new designation is proposed for the 

 Dogger ally of T. striata, figured and catalogued by Phillips, and subsequently 

 quoted by Williamson and other palaeontologists. D'Orbigny, in his ' Pro- 

 drome,' judging probably solely from the figure given by Phillips, refers it to 

 the T. tuberculoma, Agassiz, a species which, in Wiirtemberg, appears to oc- 

 cupy nearly the same geological position ; but an examination of the Yorkshire 

 specimens renders it impossible to acquiesce in this view. Many of the Testacea 

 at Blue Wick have suffered compression ; and their general condition in other 

 respects is not satisfactory ; to these obstacles to a clear comprehension of them, 

 it must be added that the Trigonia itself is very variable in the characters of its 

 costa?, which may be described as tuberculated rather than crenulated. Owing to 

 these varying conditions, it happens that the greater number of the specimens 

 differ somewhat from the little figure given by Professor Phillips, although it is 

 not unlikely that the figure in question may fairly represent some particular 

 specimen. Trigonia composita is more elongated than T. striata, but less so 

 than T. tuberculata ; the umbones are elevated and moderately recurved ; the 

 marginal and inner carinas, which are conspicuous and tuberculated, have a 

 graceful curvature; the area is moderately large, flattened, with dense and 

 delicate transverse striations, bounded by the two tuberculated carina?, and tra- 

 versed by a mesial oblique row of tubercles ; the lanceolate space is lengthened 

 and smooth. It rarely happens that the costse have the regular curvature which 

 is seen in T. striata or in T. formosa ; they often form a kind of undulation to- 

 ward the posterior side : the costee are then more oblique, and little prominent 

 toward the anterior side, they approach the carina at a less angle than in the 

 before-mentioned species, and likewise differ from them in having the largest 

 tubercles near to the carinal extremity. The most striking distinction con- 

 sists in the three rows of tubercles upon the area, and its bounding carinas, — a 

 feature which rather tends to connect it with the considerable group of species 

 allied to Trigonia clavellata. In the Dogger, at Blue Wick, it is tolerably abun- 

 dant. — J. L. 



