676 PROF. J. W. GREGORY ON [Nov. 19II, 



steep and the front part of the anterior sulcus is almost vertical 

 for nearly the full thickness of the test. 



The apical disc is opposite the widest part of the test, and the 

 area within the internal fasciole extends forwards as a flat platform, 

 from which the antero-lateral petals diverge almost at right angles. 

 Atrophy of the inner pores of the antero-lateral petals by the 

 internal fasciole has reduced them to ten pairs in the anterior zone, 

 while the posterior zone has thirteen pairs. The posterior zone is 

 very sinuous, and the middle pore-pairs are very wide. 



Large tubercles rising from the depressed scrobicular pits occur 

 in the anterior corner of the test ; there are eight before and twelve 

 behind each antero-lateral petal. 



Periproct well raised on the posterior wall, which appears to 

 slope slightly downwards posteriorly, so that the periproct would 

 not be seen from below. 



Plastron broad, slightly raised above the lateral areas, which are 

 covered with crowded coarse tubercles. The plastron expands in 

 width gradually backwards. Owing to its elevation the plastron 

 has been worn, and leaves only faint traces of the small tubercles 

 with which it was provided. 



Dimensions. — Length = 42 mm. ; breadth =-42 mm. ; height = 

 16 mm. ; length of functional part of antero-lateral petal = 12 mm. ; 

 length of postero-lateral petal = 16 mm. 



Distribution. — In yellow argillaceous limestone with Oper- 

 culum libyca : Cyrene Limestones (Aquitanian). Near Ain Sciahat, 

 Cyrene. 



Affinities. —The genera Lovenia and Sarsella are separated by 

 the presence of ampullae in the former. The side of this specimen 

 has been cut away in order to determine their presence, but they 

 appear to be absent. There are some reasons for doubting the value 

 of this character ; but, if it be accepted, this species is a Sarsella. 



The species with which, however, it offers closest resemblance 

 is the S. sulcata of Haime, which according to M. Lambert is a 

 Lovenia. 8. lamberti and S. sulcata differ, however, in several 

 well-marked characters. Thus the antero-lateral ambulacra project 

 forward in 8. sulcata more than in 8. lamberti, though they agree 

 in the number of pores and in the proportion atrophied by the 

 expansion of the internal fasciolar area. The number of big 

 depressed tubercles behind the antero-lateral petals is larger in 

 8. sulcata, there being twenty-two instead of thirteen. 8. sulcata, 

 according to Cotteau's figure 1 (pi. xxii, fig. 2), has a rounded 

 posterior end, but the specimen figured on his pi. xxiii, fig. 1, has 

 a truncate posterior end like that of 8. lamberti. 8. sulcata is 

 therefore a variable species. The excellent series of figures of 

 Breynia carinata Arch. & H. given by Duncan & Sladen 2 show 

 how variable are the most conspicuous specific characters in the 

 genera Lovenia, Sarsella, and Breynia. 



i G. Cotteau, 'Ech. Eoc, Pal. Fran 9 . : Terr. Tert.' vol. i (1885-89). 

 2 'Ech. Western Sind ' Pal. Ind. (Geol. Surv. India) ser. xiv, vol. i, pt. 3 

 (1885) pp. 343-54, pi. liv, figs. 1-9, & pi. lv, figs. 1-8. 



