LUSITAKIAN PEOYINCE. 67 



supposed to be now peculiar to tlie Mediterranean ; tte small 

 number of species show they are aberrant or expiring forms. 

 Cassidaria, and Thecidium are ancient, widely-distributed 

 genera, and the Mediterranean Thecidium occurs fossil in 

 Britlany and the Canaries. 



Thysanoteutlii3, 2 sp. Scseurgua, 1. Morrisia, 2, 



Verania, 1. Pleurobranclisea, 1. Thecidium, 1. 



Dosidicus, I. Tethys, 1. Scacchia, 2. 



Doridium, 1. Cassidaria, 6 



Icarus, 1. Pedicularia, 1. 



The genera Fasciolaria, Siliquaria, Tylodina, Notarchus, Verti- 

 cordia .2 Glavagella, and Crania, occur only in this portion of the 

 Lusitanian province. 



Amongst the peculiar species are : — 



Nassa semistriata. Argiope cuneata. Artemia lupinug. 



Fusus crispus. Clavigella angulata, Trigona nitidula. 



Tylodina Eaftuesquii. Spondylus Gussonii, Luciaopsis decussata. 



Crania rostrata. Astarte bipartita. 



u^gean Sea. Prof. E. Forbes obtained 450 species of moUusca 

 in the ^gean, belonging to the following orders : — 



Cephalopoda 4 Nudibranchs 15 Brachiopoda 8 



Pteropoda 8 Opisthobranchs 28 Lamellibranchs 143 



Nucleobranchs 7 Prosobranchs 217 Tunicafa 22 



Of these Vl were new species, but several have since been 

 found in the Atlantic, and even in Scotland.* The only marine 

 air-breather met with was Auricula myosotis. 



Black Sea. In the northern part a few Aralo- Caspian shells 

 are found, otherwise the Black Sea only differs from the Medi- 

 terranean in the paucity of its species ; Dr. Middendorjff enume- 

 rates 68 only. The water is less salt, and there is no tide, but 

 a current Hows constantly through the Dardanelles to the 

 Mediterranean, f 



LorenzJ found 178 molluscs at Quarnero, of which 75 were 

 bivalves, and 88 univalves; 75 of them extended their range 

 into the -S^gean Sea, 58 into the Boreal province. Few only 

 appeared to be peculiar to the Adriatic. 



* Trans. Brit. Assoc, (for 1843), 1844, p. 130. 



t A current from the Atlantic sets in perpetually through the Straits of Gibraltar, 

 and there is scarcely any tide ; it only amounts to one foot at Naples and the Euripus, 

 two feet at Messina, and five at Venice and the Bay of Tunis. 



t Physikalische Verhaltnisse und Vertheilung der Organismen im Quamerischen 

 Golfe. Wien, 1863. 



