PLATE XY. 



J. The Argonauta argo sailing. 

 %. OcythoU Cranchii, Leach, sitting within the shell. 

 3. Clio Borealis. 



a. The body. 



b. .. viscera seen through the common coverings. 



cc. . . tubercles of the head, and the holes into which the three lenta- 



cula on each side retire. 

 dd. branchiae and fins. 



, Pneumodermon, front view. 

 The body. 



b. 



dd. 



head, 

 mouth, 

 lips. 



e. The chin or pointed fleshy appen- 

 dage. 

 .. fins. 



g, .. branchiae. 



h. .. trunk of the branchial win. 



5. Pneumodermon, with the skin divided to shew the position of the peri- 



cardium and fleshy tunic. 

 The auricle. 

 k. pericardium. 



//. .. fleshy tunic with its longitudinal fibres. 



6. The Eolis, placed obliquely, shewing the belly and right side. 



7. ScylUea pelagica, on the right side. . 



HH. The under surface of the foot hollowed into a deep furrow, by 



which it suspends itself. 

 G. .. mouth. 

 AA. ■ ■ two tentacula. 



BC. Two pair of membranous flexible \ These and the back bear the 

 -wings. Jbranchise in the form of little u- 



D. A crest on the tail. J brous tufts. 



E. The orifice of generation. 



F. .. orifice of the anus. 



ScyU&a pelagica seen on the side of the belly. 



Se/llaa. pelagica suspended to a branch of the Fucus natans. 



phyllidia Irilineata seen on the upper side. 



aa The indentations for the upper tentacula. 



j „ .. of the anus. 



.in upper lenlaculum magnified. 



phyllidia irilineata seen underneath. 



m, The inferior tentacula, between which is the month. 



l, 4 ., branchiae of the left side t 



c. ,. orifice of generation. 



A Umax seen on the right side, the tentacula half developed. 

 aa. The great tentacula. 

 lb, .. smaller .. 



c. .. mouth, between which and the small tentacula are seen the 



papilla of the upper hp. 

 dd. ■■ foot 



e. .. posterior point of the back, whence issues the mucosity by 



which it suspends itself. 

 /. .. mantle. 

 g. .. orifice for respiration. 

 A. .. .. generation. 



