ORDER I. NUDIBRANCIII. 



1. Doris. (1) Cuv. 



Branchiae posterior 

 ranged in a circle. 



2. Polycera. Cuv. 



GENERA. 



2 Small conical ten- 

 tacula to the mouth, 

 and 2 club-shaped from 

 the upper part of the 

 mantle. 



Mouth a small trunk 

 on the fore part of the 

 mantle. 



Branchiae as in Doris, 2 Club-shaped tenta- 



but more simple and with cula before ; 4 or 6 



two membranous plates others simply pointed, 

 covering them in the mo- 

 ment of danger. 



3. Tritonia. (2) Cuv. 



Branchiae ranged along 

 the two sides of the back . 



Ditto. 



Mouth with large 

 membranous lips. 



Mouth a membranous 

 trunk without jaws. 



Mouth like a small 

 trunk . 



4. Thethys. Lin. 



Two rows of branchiae 2 Compressed tenta- 

 the whole length of the cula, with a small coni- 

 back, like bunches of fea- cal point on the edge, 

 thers ; a large, membra- 

 nous, fringed veil on the 

 head. 



5. Scyll^A. (3) Lin. 



Body compressed; foot Ditto, 

 narrow, with a furrow 

 for seizing the stems of 

 fuci : two pair of mem- 

 branous crests on the 

 back. PI. 15, fig. 7, 8, 9. 



6. Glaucus. (4) 



Body long, slim; three 4 Very 

 or four branchiae on each tentacula. 

 side, formed of long 

 thongs, disposed like fans 

 and serving as fins. 



(1) A peculiar liquor issues from a gland interlaced with the liver. They are 

 found in all seas. Their spawn is spread like gelatinous bands on stones., varecs, etc. 



(2) The orifice for the liquor is pierced to the right, and their mouth is armed 

 within by two lateral jaws, horny and sharp, and resembling shears. 



(3) The middle of the stomach is furnished with a fleshy ring, armed with sharp 

 horny blades like knives. 



(4) They are beautiful little animals inhabiting the Mediterranean and the Ocean, 

 agreeably coloured with azure and mother of pearl, and swim on their back with 

 great swiftness. They have not yet been dissected, and the species are not very 

 clearly distinguished. 



small conical Swim on their back, 



