Il8 GENERA AND SPECIES. 



aspen, J in. gills n, white, dorsal tentacles sub-conical. 



proxima, Jin. gills n, orange yellow. 



muricata, J in. yellowish white, mantle with large close set 



tubercles. 



loveni, J in. gills n, yellowish white, mantle with large 



distant tubercles. 



ulidiana, J in. gills n, pale yellow. 



diaphana, J in. gills n, white, dorsal tentacles linear. 



depressa, Jin. gills n, light brown, spotted with reddish 



brown. 

 bilamcllata, ij in. gills 20 to 29. 



Gills united at base, non-retractile 



quadrangulata, i in. gills 7, dorsal tentacles in smooth sheaths. 



pilosa, i^ in. gills 7 to 9, dorsal tentacles in toothed 



sheaths. 



Doto. (DOTONIDJE.} Plate xxxii. 



fragilis, i in. foot notched in front. 



pinnatifida, f in. foot arched in front and rounded. 



598. coronata, Jin. tubercles of gill processes tipped with purple. 



cuspidala, J in. tubercles of gill processes without purple 



tips. 



Dreissensia. (DREISSENSIIDM.} Plate vii. 



60. polymorpha, i^ in. shell mussel-shaped, and keeled in the middle 



of both valves. 



Elysia. (ELYSIID&.) Plate xxxi. 

 588. viridis, f in. body green, with bright blue metallic spots. 



There is a variety of this olivacea, which is brownish, with blue and red dots, and 

 white tips to the tentacles. 



Emarginula. (FISSURELLID&.) Plate xxi. 

 Beak overhanging 



330. rosea, % in. shell broader in front than behind. 



Beak not overhanging 



329. fissura-, J in. colour whitish, sides of slit parallel, ribs 25 



to 35- 



331. crassa, i in. white, slit wider below. 



332. cancellala, J in. white or yellowish slit a quarter as long as 



shell, shell ovate, anterior slope convex, 

 posterior slope straight, 62 to 68 radiating 

 ribs, alternately large and small. 



