574 H. p. KJERSCHOW AGERSBORG 



is fringed with two rows of cirrhi which also are highly complex 

 in structure. From an inner ganglionic axis, nerve-fibres 

 radiate to the peripheral ectoderm of the cirrhus. The exact 

 function of the tentacles, as well as of the cirrhi, is not known. 

 The tentacles are commonly called rhinophoria but, since the 

 exact function is not known, I have employed the original 

 term tentacles (dorsal tentacles) instead of the commonly 

 used term ' rhinophoria '. The cirrhi are more sensitive to 

 tactile stimulus than are the dorsal tentacles (x\gersborg, 

 1922ft: 441-3). 



4. The body-surface of M . leonina appears smooth, but 

 upon close examination it is found to be everywhere tuberculate, 

 including the sole of the foot and the ventral side of the hood ; 

 in that way this species corresponds to other members of 

 this genus. 



5. The dorsal appendages, which in M. leonina consist 

 of six pairs of foliaceous lobate structures, I have called by 

 the Linnean term papillae, instead of cerata, or branchial 

 papillae for the reason as stated by Bergh (1879 c) : ' Respira- 

 tion takes place all over the surface in Nudibranchs,' &c. 

 The papillae alternate in position ; they are subject to varia- 

 tion in structure relative to position and age (PL 27, figs. 1, 2, 

 3, and PI. 30, figs. 18-25). 



6. The foot projects in front of, and behind, the main body. 

 It is highly tul)erculate and ciliated. Internally, a fine nerve net- 

 work is seen spread throughout its length and breadth, and at 

 the posterior end it aggregates into a ganglionic centre. Fine 

 nerve fibrils are seen to pass to the ciliated ectoderm. A great 

 many mucous glands are present all through the foot, which 

 open independently through small crypts between the ecto- 

 derm cells. These glands are the pedal glands which are 

 scattered all through the foot (figs. 1, 2, 3, 9, 26, 27, 28, 29). 



7. There are three kinds of glands in the body-wall : (1) the 

 largest and most numerous are the odoriferous glands ; (2) 

 the next in size and number are the saccular mucous glands ; 

 and (3) the unicellular mucous glands (PI. 31, figs. 30, 31). 



8. The muscle system lies below the glandular fimbriated 



