16 PERMIAN FOSSILS. 



noticed, and twelve species only having been described as belonging to the earlier 

 strata/ the few species which we now bring forward may perhaps be regarded as of 

 some interest. The presence of so few species of this group in the early formations 

 tends to strengthen the remark made by M, d'Orbigny, that the Foraminifera 

 appear to have been subject to a somewhat regular progression both in character and 

 number, the simple forms occurring in the early formations, and that but rarely, and 

 the most complicated not appearing until the cretaceous, tertiary, and recent epochs, 

 and then with profusion. Further observations, however, by increasing our knowledge 

 of the microzoa of the palaeozoic rocks, may perhaps somewhat modify this interesting 

 hypothesis. 



Of the two genera, Dentalina and Textularia, found in the Magnesian Limestone, 

 the first (a simple form) is the most common, and is locally abundant ; the latter (a 

 more advanced or complex form) is stated by M. d'Orbigny to appear for the first time 

 in the Neocomian series. Prof. Ehrenberg, however, in March 1843 (Monats-Bericht 

 Berl. Akad.), described a Textularia of the Russian Carboniferous rocks, and Mr. Phillips 

 has pointed out the existence of this genus both in the Mountain-limestone, and the 

 Oolite of Yorkshire, and we have now two species to add from the Permian group. 



The specimens under notice were obtained from some thin calcareous slabs, occurring 

 on the sea coast near Byers' Quarry, between Sunderland and South Shields, composed 

 of a hard gray crystalline Limestone, with an uneven surface, here and there 

 exhibiting a covering of fine calcareous grit. The latter, almost if not quite as hard 

 and compact as the crystalline Limestone, had been subjected to the action of the 

 waves and weather, and afforded casts and shells of Mollusca, Entomostraca, and 

 Foraminifera standing in relief, and more or less perfectly preserved. The crystalline 

 Limestone also afforded, on fracture, many specimens of Entomostraca, and probably 

 may have been as rich in organic remains as the less altered gritty covering. 



Besides the species figured, a few other less distinct forms occurred in this Lime- 

 stone, as well as in a more friable and yellowish stone from Humbleton and Tunstall Hill. 



appearance of being tubuliferous. The structure of the outer rim, however, of the Nummulite, and some 

 other genera, may be truly tubular or foraminated, admitting the passage of pseudopodia. In Textularia, 

 Valvulina, Bulimina, and others, in which the shell is not hyaline, but opaque and friable, the thinned or 

 transparent spaces in the shell are fewer, and very irregular in size and distribution ; and here tubular 

 structure, both apparent and real, is altogether absent, as also in the Agathistegia, in which the shell is 

 still more homogeneous and opaque. 



1 The Carboniferous Limestones of Russia. (See Geol. Russia, vol. ii, p. 382.) Evidences of Foraminifera 

 were observed in Mountain-limestone by Messrs. Tennant and Darker in 1839, and by Mr. Lonsdale in 

 1840, but the genera were not ascertained ; and Mr. Phillips, both in 1841 (Palseoz. Foss. Devon., p. 153) 

 and in 1846 (Remains of Micros. Anim., Yorkshire, p. 5), refers to the presence of Foraminifera in the 

 Mountain-limestone, and in the Devonian and Silurian rocks. See also Mr. WUliamson's paper on some 

 Microscopic Objects, &c. (Manchest. Mem., 1847, p. 88). An additional species, Nodosaria fusuliniformis, 

 has been noticed by Prof. M'Coy in the Carb. Limestone of Tyrone (Ann. Nat. Hist., 1849). 



