34 SUPPLEMENT TO GREAT OOLITE MOLLUSCA. 



PECTKN MICHELENSIS, Buviynier. Tab. XXXIII, fig. 3. 



PECTEN CANCELLATUS, Bean, on Cornbrash Fossils, Mag. Nat. Hist., 1839 (no figure 



or description). 

 MICHF.LENSJS, Buvignier. Pal6ont. de la Meuse, Atlas, p. 24, pi. 32, fig. 7. 



Testa orbiculari, depressa maxima, concentrice ruffosa et obsolete lineis subpunctatis 

 irregulariter radiata, ad umbones costulis convexis, distantibus, regularibus radiantibus et 

 concentricis decussata ; umbonibus acutis ; auriculis in&qualibus, transverse costellatis. 

 (Buvignier. ) 



Shell orbicular, depressed, large, rugose in the adult state, with slightly defined, irregular, 

 radiating lines and large, irregular, concentric lamellae ; the umbones are acute, the auricles 

 are unequal, the posterior auricle with large, rugose, transverse striations ; the surface near 

 to the umbo has regular, radiating costae, slightly knotted where they are decussated by the 

 concentric costae, which are nearly regular, and somewhat less closely arranged than those 

 which radiate. 



The foregoing description applies to the right valve ; the change which the surface 

 undergoes in acquiring its adult condition is very striking, and is slightly indicated by the 

 few last lamellae upon the specimen figured ; a very fine example in the Scarborough 

 Museum, from the Coralline Oolite of Malton, shows that it ultimately acquired the aspect 

 of Hinnites, thus losing all regularity in its ornamentation, and having very large, irregular, 

 squamose lamellae ; the left valve has not been obtained. 



Pecten retiferus ( ' Gr. Ool. Monogr. Biv.,' p. 9, tab. i, fig. 15) approaches to it in the 

 kind of ornamentation, but has the radiating costae larger and more distant, as are also the 

 concentric lamella? ; the umbones are less acute, and the auricles, which have a different 

 figure, are more nearly equal. Under the name of Pecten cancettatus, it was inserted by 

 Mr. Bean in his list of Cornbrash fossils, but without either figure or description. The 

 splendid work of M. Buvignier on the ' Palaeontology of the Meuse' exemplifies an aged 

 specimen, together with the progressive changes which the ornamentation of the surface 

 underwent. 



Geological Positions and Localities. The specimen figured is from the Cornbrash of 

 Scarborough ; it occurs also in the Coralline Oolite of Malton ; M. Buvignier has recorded 

 it in the same formation at St. Mihiel and at Donaument. 



PECTEN ANISOPLEURUS, Buv. Tab. XXXIII, figs. 5, 5 a. 



PECTEN ANISOPLEUKUS, Buvignier. Paleont. de la Meuse, Atlas, p. 23, pi. 19, figs. 

 3135. 



Tusta subrotunda, depressa, inaquivalvi ; valva sinistra subplana, quinquecostata, lamellis 

 concentricis, Jibrosis, interdum interrupts, subtextis, ornata ; costis distantibus, convexis, 



