48 ANTHOBRANCHIATA. 



In their embryonic state these lovely fragile Mollusks are 

 supplied with little, clear, spiral shells, and swim like Pte- 

 ropods freely through the water, being furnished, at this 

 epoch of their lives, with two bead-fins and a large frontal 

 veil. As they grow, however, the shell falls off, and the 

 veil becomes modified, but is usually persistent in the 

 adult. They are universally distributed throughout all seas. 



Sub-order ANTHOBRANCHIATA. 



Gills plumose, on the hinder part of the mantle, disposed 

 in a circle, or semicircle, round the vent. 



Fam. DOEIDID^. 



Teeth, many in each cross series, sub-similar, inner often 

 smaller. Mantle-edge simple ; gills surrounding the vent, 

 on the middle of the hinder part of the back, in a common 

 cavity. 



The Dorididce form an assemblage of most attractive 

 Nudibranchs, which may be easily studied by placing them 

 in glass reservoirs of salt-water, as they are by no 

 means shy, but extend their tentacles and display their 

 branchial plumes to great advantage. In this family the 

 gills are retractile into a common cavity, and the mantle is 

 very large, either entirely, or almost, covering and concealing 

 the foot. 



Sub-fam. DORIDINiE. 



Body depressed, rounded above. Mantle convex, large, 

 simple, covering the head and foot. 



