THE EUROPEAN SEAS. 187 



of Testacea, compiled by Ed. Forbes, is here re- 

 produced. 













% 





-T3 



5 fath. 



SB 

 © 







CM 



o 



o 



CM 



in 



CO 



1 



OS 

 c- 



o 



CO 

 CM 







i. 



ii. 



iii. 



iv. 



V. 



vi. 



vii. 



viiu 



Chitons . 



7 



3 



2 







2 



2 



1 



1 







Patelliform univalves 



20 



11 



3 



2 



3 



5 



6 



6 



1 



Dentalia . 







A 



4 



A 



2 



1 



1 



2 



Z 



Spiral univalves, 

 Holostomatous 





115 



50 



40 



40 



44 



35 



28 



17 



15 



Spiral univalves, Si- 





104 



40 



27 



30 



41 



36 



» 



16 



5 



phono-stomatous 









Pteropods and Nu- 

 cleobranchs . 





12 



1 























3 



12 



Brachiopods 



8 















2 



4 



5 





3 



Lamellibranclis 



135 



38 



53 



52 



68 



58 



48 



34 



28 



JEgean total . 



407 



147 



129 



126 



162 



141 







119 



86 



66 



The system of representation in depth, which has 

 been alluded to in the notice of the fourth region, 

 is of this kind. Eepresentative forms are similar, 

 and require the tact of an experienced naturalist 

 to discriminate them. One or two examples will suf- 

 fice in order to show how such forms replace one 

 another in zones of depth. 





i. 



ii. 



iii. 



iv. 



v. 



vi. 



vii. 



viii. 



Nucula 

 Area 



Trochus • 



( emarginata . 

 ( striata . 

 fbarbata 

 J lactea . 

 i scabra . 

 (jmbricata 

 ' ( crenulatus . 

 \ exiguus 

 ( ziziphinus . 

 ( millearanus . 



min. 



•1 1 ' i ' 1 iii i 



min. 

 min. 



max. 

 min. 



max. 

 min, 



max. 



min. 

 max. 



min. 

 max. 

 min. 



min. 



max. 



min. 

 min. 

 max . 



Ii i i plli i i 



