168 



MEDITERRANEAN PROVINCE. 



[Echinus esculentus), which swarms over the rocks 

 at slight depths from the surface. 



" Outside the gulf," he continues, " is deep water ; 

 but I was disappointed in my dredging there. For 

 several leagues seaward in from fifteen to forty- 

 fathoms, I met with nothing but tenaceous mud, 

 with Turritella communis and a curious variety of 

 Oalyptrcea sinensis. The limestone rocks of this 

 coast contain in abundance the perforating c Date- 

 shells' {Lithodomus dactylus), by extracting which 

 ' the fishermen eke out their precarious livelihood.' " 



These few forms already quoted indicate at once 

 to the " Celtic " naturalist that he has moved into a 

 new zoological province. His subsequent researches 

 will show him that all here is not equally new 

 and strange ; so that, if to the foregoing he acids 

 Teredina, Solenomya, Cardita, Chama gryphoides, 

 Spondylus gaderopus, Crepidula unguiformis, Cassis 

 Saburon, Cassidaria Tyrrhena, and two or three 

 species of Mitra and Marginella, he has before 

 him the assemblage of generic difference between 

 this sea and his own. Some of these forms are 

 marginal, and occur readily, causing the testaceous 

 fauna to appear more distinct from ours than it 

 really is. 



" The greatest specific variation," observes Mr. 

 Jeffreys, "between the British Testacea and those 

 of the Mediterranean occurs in the denizens of the 

 littoral and laminarian zones, particularly in the 



