INVERTEBRATE ANIMALS. 37 



Cmt^ Cable €RBt. 



Sub-class GASTEROPODA PULMONIFERA. 



TrvsujU-wv, lungs ; <^spoo, I carry. 



Group 109.— Order OPEKCULATA. operculum, a lid. 

 Estimated number of species : recent, 835 ; British, 3 ; 

 fossil, 50 ; Tertiary. The operculate Pulmonifera attain 

 their highest development in the Polynesian Islands, 

 but are found in both hemispheres. The shells exhibit 

 remarkable varieties in form and sculpture : some are 

 cylindrical and glassy, others discoid ; many are beauti- 

 fully keeled, as may be seen in the delicately fringed 

 whorls of Trochatella constellata. The drawer is 

 crowded, but contains examples of nearlj all the generic 

 and sub-generic forms. 



IT Cyclostoma, Pupina, Helicbia, Trimcatella, 

 Assiminia, &c. 



Order INOPEKCULATA. m, without ; oper- 

 culum, a lid. 



Group 110.— Sub-order THALASSOPHILA. daXao-cra, 

 the sea ; 4^tXof, a friend. Estimated number of species: 

 recent, 98 ; British, ; fossil, 3. Tertiary. 



^ Examples of Slphonaria, Amphibola, &c. The 

 shells ^ of Slphonaria resemble those of the 

 Limpet tribe, but the animals are widely 

 distinct. 72 species are exhibited, most of 

 them presented by Mr. F. P. Marrat. 

 Upper Compartment. 



Drawings of the animals of Siphonaria and Patella. 



