664 PROP. J. W. GREGORY ON [Nov. 19H y 



to its length, and has a more even slope from the apex to the front 

 edge. CI. goirensis D. & S., 1 from the Miocene of Kach, is another 

 similar species, as it is very closely allied to CI. sub-placunarius ; 

 but it differs therefrom by its wider petals. 



Fibttlaria luciani (de Loriol) 1880. 



JSchinocyamus luciani de Loriol, 1880, ' Monogr. Ech. Nummul. Egypte ' Mem. 



Soc. Phys. Hist. Nat. Geneve, vol. xxvii, pt. 1, p. 74 & pi. ii, figs. 8-15 a. 

 Echinocyanms luciani de Loriol, 1883, ' Eoc. Ech. iEgypt.' Palseontographica, 



vol. xxx, pt. 2 (1903) p. 11 & pi. i, figs. 13 a-13 d. 

 Thqgastea luciani Fourtau, 1899, ' Rev. Ech. Foss. Egypte ' Mem. Inst. 



Egypt, vol. iii, fasc. 8, p. 642. 



Distribution. — Egypt: Middle Eocene, Mokattam and Wadi 

 el Tih, near Cairo. Cyrenaica : Middle Eocene, in white marly 

 limestone (at 1215 feet above sea-level), near the foot of the 

 escarpment north of Cyrene. 



Dimensions in millimetres: — 



Larger specimen. De Loriol's type. 



Length 5'5 3 to 11. 



Breadth 4*5 66-73 per cent, of length. 



Height 3-0 55-65 



Affinities. — The collection includes two specimens (Cy 78) of 

 a Fibularia from a bed of soft marly limestone cropping out north- 

 east of our camp at Ain Sciahat, below the Roman road to Mersa 

 Susa, and beneath the soft shelly limestone (Cy 77) on the face of 

 the upper escarpment. As only two specimens were collected, it is 

 not advisable to destroy one in order to verify the absence of the 

 septa — the essential distinction between Fibularia and Echino- 

 cyamus : for the echinoids have the height and egg-shaped form 

 characteristic of Fibularia. Agassiz indeed separated Fibularia 

 from Echinocya?nus by its subglobular form. 



De Loriol described the species as subcorneal, and remarked its 

 affinity to Fibularia. Fourtau in his ' Revision ' has transferred the 

 species to the genus Thagastea of Pomel ; but, as he says that the 

 only difference between Thagastea and Fibularia is that the former 

 is more elongated and irregular in shape, the genus appears un- 

 necessary. The smooth anterior peristomal depression, which Pomel 

 used as the essential feature of Thagastea, is even less adequate as 

 a generic character. 



The nearest allied species is the Echinocyamus rotundus of Duncan 

 & Sladen, 2 from the Upper Eocene or Khirthar Series of Sind. 

 That species is much higher than is usual in Echinocyamus ; its 

 length is 9 millimetres, its breadth 8'75 mm. and height 5 mm. ; 

 but, if E. rotundus be a Fibularia, it can be distinguished from the 

 Cyrenaican species by the upper surface rising to a sharp summit 



1 P. M. Duncan & W. P. Sladen, ' Foss. Ech. of Xachh & Kattywar ' Pal. 

 Ind. (Geol. Surv. India) ser. xiv, vol. i, pt. 4 (1883) p. 59 & pi. xii, figs. 14, 16. 



2 P. M. Duncan & W. P. Sladen, ' Foss. Ech. W. Sind ' Pal. Ind. (Geol. 

 Surv. India) ser. xiv, vol. i, pt. 3, faac. 3 (1884) p. 135 & pi. xxv, figs. 33-37. 



