MR J. W. GREGORY ON THE MALTESE FOSSIL ECHINOIDEA. 



625 



Diagnosis. — Form cordate, a broad shallow notch on the anterior margin ; it tapers 

 slightly to the posterior margin, which is abruptly truncated. Seen from the side it is 

 seen to be depressed, and with a wavy margin produced by a depression around the 

 apical system and the carinate posterior interradius. The latter overhangs posteriorly. 



The actinal surface is flat, but bulging at the posterior margin. 



Ambulacra : Anterior widest with minute pores ; interrupted by the internal fasciole. 

 Antero-lateral large, extending quite two-thirds of the distance to the ambitus ; the pores 

 of the anterior zone disappear close to the apical system. The direction of the antero- 

 lateral pair is very divergent. The postero-lateral ambulacra curve back beside the keel, 

 and bend outwards at the lower ends. The paired petals are flush with the test. 



Apical system excentric anteriorly ; four genital pores. Ethmolysian. 



Peristome excentric in front ; mouth semilunar. 



Epistroma : Abactinally a number of large tubercles set in deeply sunk scrobicules on 

 the paired interradii ; some coarse granules occur on the anterior ambulacrum ; in addi- 

 tion to these, there is a granulation of uniform minute granules. Actinally, there is a 

 broad bare band with a few granules, and on either side an area covered with deeply 

 scrobiculate tubercles. 



Fascioles : Internal fasciole sinuous, forming a key-shaped area with the apical 

 system in the centre of the expanded part. There are eight pairs of large pores on either 

 side of the area within the subanal fasciole. 



Anus large, oblong, overhung by the posterior interradius. 



Dimensions — 



Length, ..... 



55 



mm. 



Antero-lateral ambulacra : No. 



of pores 





Width, ..... 



51 



>) 



in ant. zone, . 





10- 



-11 



Height, ..... 



20 



)> 



Posterior ambulacrum : 



length, 





19 mm 



Apical system : distance from anterior 







>) )> 



width, 





6 „ 



margin, .... 



21 



» 



j> » 



No. of 



pairs of 





Mouth : distance from anterior margin, . 



13 



>> 





pores 



in ant. 





Antero-lateral ambulacra : length, 



14 



>> 





side, 





22 



„ „ width, 



5 



>» 



)> » 



No. of 



pairs of 





„ „ No. of pores in 









pores 



in post. 





post, zone, . 



13 







side, 



* 



20 



Type.— Brit. Mus., E. 3406. 















Distribution. — Malta — Globigerina Limestone. 



Remarks. — This species was originally identified by Dr Wright as Spatangus hoff- 

 manni, Goldf., and subsequently as S. ocellatus, Defr., but the occurrence of the internal 

 fasciole necessitates its removal to the Lovenia group. This was pointed out by Pro- 

 fessor Duncan,* and the species is accordingly named after him. Defrance's species is 

 a true Spatangus. 



This species differs from Sarsella peroni (Cott.)t by the shape of the internal fasciole, 

 and the proportions of the pore areas in the antero-lateral ambulacra. 



* Revision, Journ. Linn. Soc. Zool., xxiii., 1889, p. 265. 



t G. Cotteau, Ann. Soc. Agric. Lyons (4), ix., 1877, pp. 334, 335, pi. xvi. f. 3-4. 

 VOL. XXXVI. PART III. (NO. 22). 5 B 



