﻿Vol. 6 1.] TERTIABY FOSSILS OF SOMAL1LAND. 171 



Lucina gigantea, Gregorio, 'Monogr. Faun. Eocenica Ronca ' Aim. Geol. Pal. 

 Palerme, pt. xxi (1896) pp. 94, 95 & pi. xvi, figs. 4-10; P. Oppenheim, 

 Palseontographica, vol. xliii (1896) p. 152 & ibid. vol. xxx, pt. iii (1903) p. 129. 



This specimen consists of a large but rather rough limestone-cast 

 with compressed valves, related probably to this species. The 

 adductor-scar markings are well defined, and the pallial line can 

 be seen for some distance in the ventral region accompanied by 

 some fine vertical striations. There is also a strong indication of 

 the long, ligulate, anterior adductor-scar on the lateral face of the 

 right valve, which is of rather crescentic shape. Large forms of 

 Lucinidse are very characteristic of the Eocene Period, being fre- 

 quently found in the Paris-Basin area ; in the neighbourhood of Ronca 

 and Monte Postale (Italy); and in the Xummulitic rocks of Egypt and 

 India. Another species, with which the specimen from Somaliland 

 may be compared, attains an even larger size than gigantea : this 

 is the Lucina corba-rica, var. regular is of Leymerie, 1 which belongs 

 to the Ypresian stage of the Eocene, 2 situated immediately below 

 the Lutetian ; but that species possesses much more convex valves, 

 although somewhat similar in general contour. Limestone-casts 

 of L. Corharica, var. regularis are found in the Lower Eocene deposits 

 of Farafra, in the Libyan Desert of Egypt. 



Dimensions in millimetres. 



Unibono- ventral =85 I Maximum convexity with closed 



Antero-posterior =90 | valves =33 



Locality. — Garrasgooi, 5 miles south-west of L T 2)per Sheikh. 



Collector. — Major II. GL Edwards Leckie. 



Matrix. — Limestone occurring below the more cherty beds. 



Lucina cf. thebaica (Zittel), Oppenheim. (PI. XX, figs. 4 & 5.) 



Lucina thebaica, Zittel, Palseontographica, vol. xxx, pt. i (1883) pp. 100, 

 102, etc. (list-name only j species neither figured nor described) : P. Oppen- 

 heim, ibid. pt. iii (1903) p. 128 & pi. xiii, figs. 3-3 a. 



This species of shell, although known under Zittel"s list-name 

 of Lucina thebaica since 1883, has only just been figured and 

 described by Dr. Oppenheim. It is of common occurrence in 

 Egypt, and characterizes the Middle Suessonian or the ' Libysche 

 Stufe ' of Zittel. The majority of the specimens that have come 

 under my observation have a greater antero-posterior measurement 

 than umbono-ventral, although Dr. Oppenheim's figures represent 

 a shell having almost equal measurements. 



The specimen from Somaliland is not so ventricose as those from 

 Egypt, but it has much the form of this species, besides possessing 

 similar subcentral beaks, and a sculpture showing indistinct con- 

 centric lines as well as straight longitudinal striations radiating 

 from the summits, a character so frequently seen in members of 

 the Lucinidge. Both valves (closed) are represented in the specimen 



1 'Mem. sur le Terrain a, Nnmmulites des Corbieres, etc.' Mem. Soc. Geol. 

 France, ser. 2, vol. i (1846) pt. ii, p. 361 & pi. xiv, fig. 5. 



A. de Lapparent, « Traite de Geologic ' 4th ed. (1900) p. 14: 



>.>. 



