28 INVERTEBRATE ANIMALS. 



Group 77.— Family CHITONID^. x'^'"". a coat of mail. 

 Estimated number of species : recent, 255 ; British, 11 ; 

 fossil, 30, from the Devonian upwards. 



^ Examples of Lophyrus, Tonicia, Lorica, Crypio- 

 plax = Chitonellus, Mopalia, &c. 

 Upper Compartment, 



Plates of the shell of Leptochiton, separated to 

 illustrate the homology of the last plate with 

 the entire shell of Patella. 



Group 78.— Family PATELLIDiE and allies. jx^/eZirt, a 



dish ; Limpets. Estimated number of species : recent, 



142 ; British 7 ; fossil, 100 ; from the Silurian upwards. 



H Examples of Tectura, Scutellina, Gadinia, 



Nacella, &c. 



Group 79.— Families FISSURELLID^ & DENTALID^. 

 Duck's-bill Limpets, Key-hole Limpets, Tooth-shells. 

 Estimated number of species : recent, 141 ; British 7 ; 

 fossil, 144. Devonian, &c. 



The Dentalidce form the sub-class Scapliopoda 

 of Bronn. Their mode of development is 

 singularly interesting, and they are supposed 

 to form a link between the bivalve and univalve 

 Mollusca. 

 IT Examples of Antalis, Scutvs = Parmophorus, 

 Emarginula, Cemoria, Lucapina, Tugali, Cra- 

 nopsis, Macrochisma, &c. 



Section PODOPHTHALMA. ttouc, foot ; ocf;9«A^oc, eye. 

 Eyes on foot-stalks. 



Group 80.— Family HALIOTID^. SiXtoc, marine, ouc, ear. 

 Estimated number of species : recent, 74 ; British, 1 ; 

 fossil, 4. Miocene. 



