F. P. MeniieU — Archcean Stratigraphy. 255 



Order ATELOSTOMATA. 



Brissus caeinatus (Lamk.). 



Raised beach, north of Qosseir. J 2110. 

 Brissus (?) carinatus (Lamk.). 



Abu Shigeli, 560 feet above sea-level. J 1624. 



Wadi Abu Shigeli, 380 feet above sea-level. K 1660. 



Indeterminable cast of perhaps a Schizaster, allied to gibberulus, 

 Ag., or perhaps a Brissopsis. 

 Eaised beach, 300 feet above sea-level, Wadi Hamrawein. 

 K 1553. 



? Schizaster gibberulus, Ag. 



600 feet above sea-level, Camp 4, Wadi Hamrawein. K 1638. 

 LovENiA ELONGATA (Gray). 



Shore, Dahab. L 3524. 



EXPLAXATIOX OF PLATE XI. 



Fig. 8. — Thijleehinus quincmicialis, n.sp. Cenomanian : marls at head of Wadi 

 Ethal, Sinai. L 3872. Collected by the late T. Barron, Esq. 

 8ff, a specimen from the side. Nat. size. 

 8i, part of the ambitus, showing the plan of the interambulacral tubercles. 



X 3 diam. 

 8c, two compound ambulacral plates fi'om the same, x 4 diam. 

 Fig. 9. — Thylechimis trigrannlatus, n.sp. Cenomanian : marls at head of Wadi Bthal, 

 Sinai. L 3872. Collected by the late T. Barron, Esq. 

 9(?., test from below. Nat. size. 

 'db, from the side. Nat. size. 



9c, upper part of an ambulacrum, showing the structure of the plates, x 4 diam. 

 2d, part of an interambulacrum at the ambitus, x 4 diam. 

 Fig. 10. — Coptosoma gunnehensis, n.sp. Cenomanian (?) : Jebel Gunneh, Sinai. 

 L 3506. Collected by Dr. W. F. Hume. 

 10«, b, type-specimen from above, and from the side. Nat. size. 

 10c, a compound ambital ambidacral plate, x 4 diam. 

 \Qcl, ambital interambulacral plates, x 4 diam. 

 Figs. 11-14. — Echinolampas feiranensis, n.s-p. Miocene: south of "Wadi Feiran, 

 Sinai. L 4204. Collected by the late T. Barron, Esq. 

 11, 12, the tj-pe-specimen from above and from the side. Nat. size. 



13, a small specimen from the side. Nat. size. 



14, base of a thu-d specimen. Nat. size. 



Fig. 15. — Micropedina cotteaui, Coquand. Ambital plates (after Cotteau). 



[Erratum. — In Geol. Mag., May number, p. 227, in Explanation 

 of Plate X, Fig. 3, Acanthechinopsis Immei, n.sp., is, by an error, 

 printed A. barroni, n.sp. It is correctly printed as A. Jiumei on 

 p. 219, and also in list of species on p. 250. — Edit. Geol. Mag.] 



III. — Some Notes on Arch^an Stratigraphy. 

 By F. P. Mennell, F.G.S. 



MUCH has been written concerning the Archasan rocks from 

 a petrographical point of view, but their structural relations 

 have as a rule received little attention. I do not wish to be under- 

 stood as overlooking the work that has been done in England, and 

 especially in America, of late, and which has added so much to our 



