Vol. 67.] THE FOSSIL ECHINOIDEA OF CTRENATCA. 663 



Affinities. — This Cyrenean Clypeaster agrees so closely in all 

 character?, except the form and length of the petals, with CI. bi- 

 arritzensis, that it seems wiser to leave it in that species, but as a 

 distinct variety. 



As CI. biarritzensis has not been recorded from Egypt, it was 

 natural first to compare the specimens with the flat Upper Eocene 

 Clypeaster breunigi of Laube, which agrees in general shape and 

 has been recorded from the district east of Siwa. C. breunigi is 

 either a very variable species, or else too manj' echinoids have been 

 referred to it. The two specimens from Cvrene differ from Laube's 

 type of CI. breunigi in the absence of the vertical undulation of 

 the margin of the test ; but that character is not shown in the 

 specimens from east of Siwa, or from Sta. Giustina near Possagno, 

 referred to CI. breunigi by P. de Loriol 1 and Dr. Oppenheim 2 re- 

 spectively. De Loriol's specimens also differ from Laube's type 

 in the character of the petals, which the former described as ' am 

 Ende gerundet und weit offen ' ; and Laube also says that the 

 petals are ' vorne weit offen,' but his figures represent them as 

 nearly closed. Dr. Oppenheim's specimen, on the other hand, is a 

 long oval echiuoid, with short and nearly closed petals. It is 

 only 30 mm. long, and so may be a young form : but he 3 suggests 

 that it is a Laganum. 



It seems to me very doubtful whether Laube's, P. de Loriol's, and 

 Oppenheim's varieties can all remain in one species. They at least 

 require distinction as well-marked varieties, as follows : — 



1. Var. typica of Laube. Form pentagonal ; apex blunt, and slopes leading 

 to it convex ; margin thickened and undulating vertically ; petals long. 

 (Character of outer ends of petals uncertain.) 



2. Var. lorioli nov. ; based on P. de Loriol's type. Form pentagonal; apex 

 as a well-raised point, with slopes leading to it concave ; margin thin and flat ; 

 petals long and open at their outer end. 



3. Var. oppenheimi nov. or sp. nov. ; based on Dr. Oppenheim's type. Test 

 small; form oval ; margin apparently thickened, but flat ; summit blunt ; petals 

 short and closed. This form is probably a distinct species. 



Of these three varieties, the specimens from the Operculina- 

 Limestone at Ain Sciahat agree best with the var. lorioli ; but 

 they differ from it by having shorter, broad, and more distinctly 

 closed petals. 



CI. subplacunarius Euchs i is a Miocene species from Siwa, which 

 offers some striking resemblances to CI. biarritzensis ; but CI. sub- 

 placunarius has longer petals, and they are represented on Euchs's 

 figures as quite closed; the test, moreover, is flatter in proportion 



1 P. de Loriol, 'Eoc Ech. iEgypt.' Palaeontographica, vol. xxx, pt. 2 Q903) 

 p. 12&pl. i, figs. 18-19 a. 



2 P. Oppenheim, ' Die Priabonaschichten & ihre Fauna ' Palaeontographica 

 vol. xlvii (1900-1901) p. 92 & pi. xv, fig. 18. 



3 Id. 'Rev. Tert. Ech. Venet. &c.' Zeitschr. Deutsch. Geol. Gesellsch. vol. liv 

 (1902) p. 190. 



4 'Beitr. Kennt. Xliocanfauna iEgyptens & der Libyschen Wiiste ' Paheonto- 

 graphici. vol. xxx, pt. 1 (1883) p. 47 [29] & pi. xvi [xi] figs. 1-3. 



