TRITONIDiE. S25 



PoLYCERA quadrilmeata, P. Lessoni, and P, ocellata are 

 very pretty little Nudibranchs^ having a veil, or border, 

 passing from the front of the head to the region of the gills, 

 which are large and branched. The P. ocellata- is beauti- 

 fully marked with circular eye-like spots on its dark green 

 body. 



Ancula cnstata presents a very lively appearance : he 

 has no veil, but his branchiae are surrounded by filaments, 

 and his long, spirally-laminated tentacles have projecting 

 filaments at their base. 



The family of Tritonidji: have the gills arranged in two 

 rows along the back. 



In Tritonia the gills are star-like and feathery, and, with 

 the fringed double veil in front of the head and fringed 

 tentacles, give altogether a very complicated appearance to 

 this animal, which exhibits prismatic colours. The species 

 are — T. Homhergiij T. plebeja, T. lineata. 



ScY'LLB.A pelac/ica, which lives on floating seaweeds, and 

 scarcely attains, in the British seas, half an inch in length, 

 has tentacles which can be drawn in and out through sheaths, 

 and a pair of wing-like borders along the back, with lobes, 

 on the iimer surface of which project very small, branching 

 gills. 



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