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. dOrbigny, that the Foraminifera 
appear to have been subject toa 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 paleeozoic 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 crystallme 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 (Palzeoz. 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. Williamson’s paper on some 
Microscopic Objects, &c. (Manchest. Mem., 1847, p. 88). Anadditional species, Nodosaria fusuliniformis, 
has been noticed by Prof. M‘Coy in the Carb. Limestone of Tyrone (Ann. Nat. Hist., 1849). 
