158 Dr. J. W. Gregory — Egyptian Echinoidea. 



a considerable resemblance to tbe JSupatagus SloTcutensis, Fucbs,^ 

 which has, however, a more cordate or elliptical test. 



Genus HEMIASTER, Desor, 1847. 



1. Hemiaster Schweinfurthi, De Loriol, 1883. 



" Beitr. libysch. Wiiste," vol. ii, pt. 1, p. 34, pi. viii, figs. 3-5. 



Distribution. — Libyan Series : El Guss Abu Said, west of 



Farafrah (De Loriol-le-Fort) ; Coll. Geol. Surv. Egypt, ex 



Nos. 862-3. 



PEETCOSMUS, L. Ag., 1847. 



1. Pericosmus latus, Ag. & Des., 1847. 

 Agassiz & Desor., op. cit., p. 19, pi. vi, figs, xvi, 1. 

 Remarks. — This well-known echinid is represented in the col- 

 lection by two specimens from tbe Miocene (Geol. Surv. Coll. 

 Egypt, No. 964). They agree with Agassiz's cast (M 23), but differ 

 slightly from Agassiz & Desor's figure by the fact that posteriorly 

 the test slightly overhangs the periproct, which cannot be seen from 

 above. The specimens agree with Cotteau's admirable description of 

 the species;^ and the posterior extremity of the test agrees with his 

 figure of P. Orbignyi, Cott., to which he applies the same description 

 as to P. latns. Hence the Egyptian form agrees with Cotteau's 

 description better than with the original figure. The echinids differ 

 from P. Orbignyi, Cott., by the greater equality of length and breadth, 

 the dimensions being 75 mm. and 76 mm. respectively. 



2. Pericosmus Peroni, Cott. 



G. Cotteau, " Faune terr. tert. Corse " : Ann. Soc. Agric. Lyons, 



ser. 4, vol. ix, 1877, p. 314, pi. xiv, figs. 3, 4. 



Distribution. — Helvetian : Corsica ; Egypt ; Coll. Geol. Surv. 

 Egypt, No. 659. 



The collection contains three broken Pericosmi, which have the 

 anterior apex, steep anterior slope, and long posterior slope 

 characteristic of P. Peroni, Cott. Two of the three echinids are 

 too broken for satisfactory determination, but a third shows the form 

 of P. Peroni fairly well. 



Genus LINTHIA, Merian, 1853. 



1. LiNTHiA AscHERsoNi, De Loriol, 1883. 



" Beitr. libysch. Wiiste," vol. ii, pt. 1, p. 37, pi. ix, figs. 1-4. 



Distribution. — Libyan Series : Gebel Ter, near Esneb, and west 



of Farafrah (De Loriol-le-Fort) ; Coll. Geol. Surv. Egypt, ex 



Nos. 862-3. 



2. LiNTHIA ESNEHENSIS — AsCHERSONI. 



Linthia Esnehensis, De Loriol, 1883 : " Beitr. libysch. Wiiste," vol. ii, 



pt. 1, p. 39, pi. ix, figs. 5, 6. 

 L. Aschersoni, De Loriol, 1883 : ibid., p. 37, pi. ix, figs. 1-4. 



1 Fuchs, " Tert. Ech. Persien" : Sitz. Ak. Wiss. "Wien, vol. Ixxxi, pt. 1 (1880), 

 p. 100, pL, figs. 17-20. 



^ G. Cotteau, " Fauue terr. tert. Corse" : Ann. Soc. Agric. Lyons, ser. 4, vol. ix, 

 pp. 310-12. 



