NEWTON : LOWEB, TERTIARY MOLLUSCA OF THE FAYUM. 77 



re"-ion, and is doubtless closely allied to Fiisus scalaris of Lamarck, 

 fouud in the Lutetian and Bartonian Beds of Europe, excellent figures 

 of -n-hich are to be seen in Desbaves's Descr. Coq. Foss. Paris, vol. ii, 

 p. 525, pi. Ixxii, figs. 13, 14, 1835. It differs, howeyer, not only in 

 size, but in the possession of the widely excavated sulcation, which 

 forms so prominent a character beneath the margin of the projecting 

 rampe. This sulcation has a maximum width of 15 millimetres, 

 the rampe also offering a similar measurement. There is no corre- 

 sponding furrow in Lamarck's species referred to, and only a slight 

 depression exists, which merges rapidly into the ordinary inflation of 

 the whorl. The Fayum shell has besides vertically-sided whorls to 

 the spire, whereas in scalaris they are gently sloping. The smoothness 

 of the projecting margins would also separate it from Murex longcevus, 

 which, according to Solander's old figures, pi. ii, fig. 40, and pi. vi, 

 fig. 73, exhibits a form with mostly irregular and spinous outer margins 

 to the sutural shelf or rampe. Clavalithes and its species have been 

 studied by Dr. A. W. Grabau, and his work on the Fhylogeny of 

 Fusus and its Allies (Smithsonian Miscellaneous Collections, vol. xliv, 

 No. 1417, p. 117, 1904) supplies us with much valuable knowledge on 

 the evolutionary characters of this genus. According to M. Cossmann 

 [Essais de Paleoconchologie Comparee. 1901, pt. iv, p. 18) the genus 

 ranges through the Eocene, Oligocene, Miocene, and Pliocene forma- 

 tions, and a well-characterized species lives at the present day in 

 Polynesia {C. serotina. Hinds). 



I have united the name of Mr. Beadnell with this fine example of 

 Clavalithes in recognition of his critical and careful work on the 

 geological structure of the Eayum depression. 



Formation. — Lutetian (Middle Eocene). 



Locality. — Near Qasr el Sagha (Dr. C. W. Andrews). 



Clavalithes Solanderi, Grabau. PI. IV, Fig. 3. 



Murex lo7iy(evus, Solander, Fossilia IIa7itonie7isia, 1766, p. 22, pl. viii, 



fig. 93 {non figs. 40 and 73 — the true long^vtis). 

 Fusus longcBvus, J. Sowerby, J/«V«(??-rt^ Conchology, 1814, vol. i, pl. Ixiii. 

 Clavalithes Solanderi, Grabau, Smithsonian Miscellaneous Collections, 



1904, No. 1417, p. 123, pl. xiv, figs. 5, 6, pl. xv, figs. 1, 2, and 



text-figs. pp. 123-5. 

 C. longcsvus, Oppenheim, Palseontographica, vol. xxx, pt. iii, sect. 2, 



p. 315, 1906, non Solander. 

 Remarlcs. — This is a form separated by Dr. Gi'abau from the true 

 Jfurex longcevus of Solander, which possesses irregular and spinous 

 outer margins to the posterior shelves of the volutions. The same 

 author regards as a gerontic example of this species James Sowerby's 

 Fums longavns, figured in 1814, pointing out that the spinous 

 prolongations seen on that specimen are the result of age, and that 

 they are only present on the sutural platform of the last whorl. The 

 Fayum fossil appears to be of medium size, consisting of about seven 

 volutions which are well elevated, closely fitting, and very narrowly 

 shelved. Well-marked sculpture is seen on the three earliest whorls, 

 consisting of fairly distant and swollen longitudinal costee crossed by 



