Molluscan Fauna of the Gulf of Sues. 



389 



varieties and geographical species, if the same type shall have 

 become diffused over distant regions, gradually assuming new- 

 characters. 



" It may reasonably be supposed, in the present case, that 

 the species which in tolerably remote times [e.g. the Pliocene 

 period) passed from the Mediterranean to the Arabian Gulf 

 have undergone very considerable alterations of form, and 

 have originated certain equivalent species^ while those whose 

 passage from one sea to the other was effected at a later (the 

 Postpliocene) period have formed our equivalent varieties.'''' 



Issel then proceeds to give the following lists, which I have 

 slightly rearranged for the sake of clearness : — 



Mediterranean Species, 



GastroclifBua dubia, Penn% 

 Soleciirtus strigilatas, L. 

 Area lactea, L. 

 Nassa costulata, Ren, 



Mediterranean Species. 



Tellina exi^ua, Poli. 



serrata, Ren, 



Tapes geographicus, Ginel. 

 Artemis exoleta, L, 

 Cardium edule, L. 



■ minimum, Phil. 



Cardita sulcata, Brng. 



trapezium, L. 



Diplodonta rotundata, Mont, 

 Lucina reticulata, Poli, 

 Area diluvii, Lam. 

 Modiola adriatica, Lam. 

 Lima squamosa, Latn. 

 Marginella minuta, Pfr. 



clandestina, Br, 



miliai'ia, L. 



Purpura hajmastoma, L. 

 Nassa gibbosula, L. 

 Ceritliium vulgatum, L. 



conieum, Bluinv. 



Pliiline aperta, L. 

 Ringicula bueeinea, Ren. 

 Eulima Pbilippii, Weinh. 

 Neritina viridis, L. 

 Fissurella grseca, Z. 

 Chiton siculus, Gray. 



Equivalent Varieties in the Red Sea. 



Gastrochsena dubia, Perm., var. 

 Solecurtus strigilatus, L., var. 

 Area lactea, L., var. erythroea. 

 Nassa costulata, Ren., var. erjthrsea. 



Equivalent Species in the Red Sea, 



Tellina arsinoensis, Isset 



Belelieriaua, Sow. 



Tapes Deshayesii, Hani, 

 Artemis radiata. Reeve. 

 Cardium istkmicum, Issel. 



sueziense, Issel. 



Cardita angisulcata. Reeve. 



variegata, Brmj. 



Diplodonta Saviguyi, Vaill. 

 Lucina erythraea, Issel, 

 Area auriculata, Lam, 

 Modiola, sp. 

 Lima buUii'era, Desh. 

 Marginella sueziensis, Iss. 



' pygmaia, Iss. 



Savignyi, Iss. 



Purpura, sp. 



Nassa circumcincta, Reeve. 



Cerithium Riippelli, Phil, 



Caillaudi, Pot. 4- Mic/i. 



Philine Vaillanti, Iss. 

 Ringicida acuta, Phil. 

 Eulima Gentilomiana, Iss, 

 Neritina Feuilleti, Aud. 

 Fissurella Riippellii, Soto. 

 Chiton affinis, Iss, 



These interesting, and in many respects valuable, remarks of 

 Issel appear to me to be open to a certain amount of criticism. 

 And, first, as to his denial of the term " geographical variety " 

 to Red-Sea " equivalents " of Mediterranean species. He 



Ann. (fc Mag. N. Hist. Ser. 5. Vol xviii. 27 



