a. B. Neicton — Fossils from Nubian Sandstone, Egi/pt. 393 



arrangement of the ridges and grooves anteriorly than on the opposing 

 side, and so producing a posterior curvature of the urabonal region. 

 In its actual marginal contour, judging from the lateral aspect, it 

 follows very much the lines of Zittel's /. Cripsi, var. typica, a Gosau 

 species of Campauian age (Denksch. k. Akad. AViss. Math. I^at., 1866, 

 vol. XXV, p. 98, pi. xiv, fig. 1), though not so rounded anteriorly 

 where the costfe are more or less vertically disposed, especially on the 

 right valve. Again, the umbonal region of the Gosau shell is much 

 nearer the anterior margin, besides exhibiting a strong anterior 

 obliquity ; the costa? are also more numerous, and the valves have not 

 the prominently arched feature of the specimen from Egypt. In 

 general form, therefore, and sculpture characters the specimen favours 

 an Upper Cretaceous horizon, and it may reasonably be regarded as 

 Senonian ; in fact, it is more than possible that its real place in the 

 series would be the Campanian stage of that period, as specified on 

 Blanckenhorn's manuscript label accompanying the specimen, because 

 it is in that stage the so-called Cripsi and its allies are more generally 

 found in the world's Cretaceous regions, such as the United States, 

 India, Japan, etc. 



Occurrence. — The only specimen available is in a good state of 

 preservation with both valves in the closed position, shell structure 

 being seen in places with the delicate surface lineations. The margins 

 ai-e rather imperfect, especially on the left anterior side, where there is 

 evidence of crushing, which was probably effected during the process 

 of fossilization. Since its arrival from Egypt a large part of the 

 matrix of the left valve has been skilfully removed by Mr. Richard 

 Hall, the senior Formatore of the British Museum (Natural History), 

 thus exposing the centrally arched elevation and the extensive areas of 

 depression at the base and rear. Through mineralization and wind 

 erosion the right valve has to a great extent lost the surface and 

 ornamentation of the umbonal region, but all its later characters are 

 well displayed. The matrix is highly ferruginous and of limonite 

 character, being mostly of a reddish-brick colour. Where wind erosion 

 has taken place through long exposure, the surface of the valves 

 is quite lustrous and polished and of a blackish-brown metallic 

 appearance. There are some obscure remains of Annelid tubes on this 

 specimen which from their fineness might probably be referred to 

 Galeolaria filiformia. In a recent letter Dr. John Ball kindly furnished 

 the following particulars as to the locality where he was fortunate 

 enougli to discover this unique Tnoceramus : — "It was obtained from 

 near the west-end of the Aswan dam, on the west bank of the Nile, 

 during excavations for a small reservoir, and, as far as I remember, it 

 was quite low down in the local series not more than 20 metres above 

 the old igneous rocks. From the adherent matter you will see it came 

 from one of the more ferruginous beds in the sandstone." Soon after 

 this information was sent. Dr. Ball, then on vacation in England, 

 called at the British Museum and supplied some further details as to 

 the occurrence of the genus in this part of Egypt. He had sub- 

 sequently found fragments of another Inoceramiis, of what might be the 

 same species, near the triangulation station of Abajaj, which is about 

 17 kilometres E.N.E. of Aswan on the east bank of the Nile, in 



