INVERTEBRATE ANIMALS. 27 



Section i. — Aiolobranchiata. aloXoc, changeable. Gills 

 in parallel rows. 



•n" Coloured models of Nudibranclis from the Mersey ; 

 Tritonia, Eolis, &c. 



Section ii. — Anthobranchiata. avQoi, a flower. Gills 

 in the form of a flower. 



^ Coloured models of Nudibranchs, Doris, &c. 



Upper Compartment. 

 Coloured drawings and specimens in spirits. 



Group 76.— Sub-order TECTIBRANCHIATA. tectus, 

 covered. Gills protected by a shell, or by the mantle. 

 Estimated number of species : recent, 338 ; British 13 ; 

 fossil, 100. Trias, &c. 



The animals frequent weedy shores and coral reefs : 

 their bodies often exhibit lively colours, and 

 are frequently much larger than the shells 

 which protect the respiratory organs. 

 ^ Examples of most of the genera in the families. 

 Act(Bonid(B = Tornatellidce, Aplnsiridce, Cyli- 

 chnidce, Bidlidce, Philinidce, Lophocercidce, 

 Aplysiida, Pic urohi -a n cMdce. 



Order PROSOBRANCHIATA. TzpS^aov, in front; 

 ^payx^'ia, gills. A very extensive order, comprising most 

 of the univalve Sea-shells best known in collections. 



Sub-order SCUTIBRANCHIATA. scutum, a 

 shield. Animals chiefly littoral in their habits, living 

 on rocks or sea-weeds near the shore. 



Section EDRIOPHTHALMA. Upa, a seat; 

 6(^^aKiJ,oc, the eye. Eyes sessile. Shell, in the adult, 

 conical, not spiral. 



