LUSITANIAN PEOYINCE. 67 



supposed to be now peculiar to the Mediterranean ; the 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 

 Brittany and the Canaries. 



Thysanoteuthi3, 2 sp. Sceeurgus, 1. Morrisia, 2. 



Verania, 1. Pleurobranchsea, 1. Thecidium, 1, 



Dosidicufl, 1. Tethj's, 1, Scacchia, 2. 



Doridium, 1.. Cassidaria, 6 



Icarus, I. Pedicularia, 1. 



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

 cordia ? Clavagella, and Crania, occur only in this portion of the 

 Lusitanian province. 



Amongst the peculiar species are : — 



Nassa semistriata. Argiope cuneata. Artemis lupinus. 



Fusus crispus. Clavigella angulata, Trigona nitidula. 



Tylodina Rafinesquii. Spondylus Gussonii. Lucinopsis decussata. 



Crania rostrata. Astarte bipartita. 



JEgean Sea. Prof. E. Forbes obtained 450 species of mollusca 

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



Cephalopoda 4 Nudibranchs 15 Brachiopoda 8 



Pteropoda 8 Opisthobranchs 28 Lamellibrancha 143 



Nucleobrancha 7 Prosobranchs 217 Tunicata 22 



Of these Yl 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. Middendorff enume- 

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

 a current flows constantly through the Dardanelles to the 

 Mediterranean, t 



LorenzJ found 178 molluscs at Quarnero, of which 75 were 

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

 into the ^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 PhysikaJische Verhjlltnisse und Vertheilung der Organismen im Quamerischen 

 Golfe. Wien, 1863. 



