The fossiliferous limestone (No. 3.) is regarded by Mr. King as a deep-water formation, from the numerous delicate corals which it includes. One of these, Fenestella retiformis ([fig. 336.]), is a very variable species, and has received many different names. It sometimes attains a large size, measuring 8 inches in width. The same zoophyte is also found abundantly in the Permian of Germany.
Fig. 336.
- a. Fenestella retiformis, Schlot.
- Syn. Gorgonia infundibuliformis, Goldf.; Retepora flustracea, Phillips.
- b. Part of the same highly magnified.
Magnesian limestone, Humbleton Hill, near Sunderland.[303-A]
Shells of the genera Spirifer and Productus, which do not occur in strata newer than the Permian, are abundant in this division of the series in the ordinary yellow magnesian limestone. (See [figs. 337], [338.])
Fig. 337.
