IGO PERMIAN FOSSILS. 



Gervillia ? Geinitz, Gaea von Sachsen, p. 96, 1843. 



Mytilus acuminatus, J. de C. Sow. De Verneuil, Bull. Soc. G60I. de France, 2"" serie, 



vol. i, p. 32, 1844. 



— — „ Geol. Russ., vol. i, p. 224, 1845. 



— Hausmanni, Goldfuss. Geinitz, Grundriss, p. 453, 1846. 



— ACUMINATUS, J. de C. Sow. Tennant, Strat. List, p. 88, 1847. 



— Hausmanni, Goldfuss. King, Catalogue, p. 9, 1848. 



— ACUMINATUS, J. de C. Sow. Howse, Trans. T. N. F. C, vol. i, p. 248, 1848. 



— H.AVSMA.iiNi, Goldfuss. Geinitz, Versteinerungen, pp. 9, 10, pi. iv, figs. 12, &c., 



1848. 



Diagnosis. — " Ovate, acuminate, the laminae of the shell having the appearance of 

 scales ; length more than an inch." J. de C. Sowerby.^ 



Having examined the originals of this species in Mr. J. de C. Sowerby's collection, 

 I have ascertained that they are identical with the shells noticed in the above 

 synonymy.^ 



As J. de C. Sowerby and Goldfuss have overlooked two or three important 

 characters of this interesting species, it is necessary for me to add, that it is inequi- 

 valved ; has ecurved umbones, a horizontal septum within the umbonal cavity of each 

 valve, and a wide longitudinally-grooved cartilage-furrow or fulcrum. Its muscular 

 system has already been noticed ; but it may be added, that the anterior visceral or 

 pedal muscles, judging from the position of their impressions (vide PL XIV, fig. 7 c), 

 have been situated much further back than is usual in Mytilus : the relative position of 

 the posterior adductor and posterior visceral muscular impressions is correctly repre- 

 sented in the figure just noticed : the pallial line is even more strongly displayed on the 

 fossil than it is in fig. 6. It is very often found nearly smooth, as in fig. 3 ; but under 

 more favorable conditions, its squamose character, which results from the prominency 

 of the incremental laminae, is finely displayed, as in the specimen represented in fig. 4. 



Mytilus squamosus is a widely-distributed species. " It occurs in considerable 

 abundance near Ferry Bridge, but generally in the form of casts" (Sedgwick, Geo]. 

 Trans., 2d series, vol. iii, p. 120). The instructive specimen represented in PI. XIV, 

 figs. 6, 7, was collected by Mr. Binney at Hampole, in Yorkshire. It also occurs at 

 Tunstall Hill, Dalton-le-Dale, Humbleton Quarry, and Silksworth. Dr. Geinitz records 

 its occurrence in the upper Zechstein of Paschkowitz, Cosma, Lehndorf, Sommeritz, 

 SchmoUn, Roschiitz, Kamsdorf, Elgersburg, Roda, Salzungen, Ahlstedt, Osterode, and 

 Neuhof ; also in the Dolomite of Miihlberg and Scharzfeld. 



1 Trans. Geol. Soc. Lond., 2d series, vol. iii, p. 120. The following is Dr. Goldfuss's diagnosis : "Myt. 

 testa ovata-acuta convexa lamellosa, umbonibus acutis, margine cardinali recto, latere inferiore decUvi, lineis 

 concentricis subdistantibus." (Petrefacta, p. 168.) 



2 Mytilus Hausmanni, Goldf., was incorrectly identified with Modiola acuminata in my ' Catalogue,' p. 9. 



