528 H. p. KJERSCHOW AGERSBORG 



4. The Body-wall. 

 (1) The Odoriferous Glands. 

 The entire surface of the body of M . 1 e o n i n a is fimbriated 

 or tufted, although it is not recognizable to the naked eye, 

 but it is easily detectable with the aid of a lens (figs. 6, Ex, 

 25, Thr, 26, 27, Thr, 31, Pec). In this respect it resembles 

 M. rosea Eang, M. pilosa Pease, M. papillosa de 

 Filippi, M . f i m b r i a t a Alder and Hancock, M.bucephala 

 Bergh, and also Tethys fimbriata Linnaeus (s. fimbria, 

 Bohascht, Delle Chiais). Closely associated with the fimbriated 

 ectoderm are several kinds of glands (PI. 31, fig. 30, Glo, Svi, 

 Um). There are at least three kinds of these glands : (1) odori- 

 ferous (Glo), (2) saccular mucous (Sm), and (3) unicellular 

 mucous {Um). The former is the largest of the three and 

 most numerous (PI. 27, figs. 4, Go, 7). In structure, the odori- 

 ferous and saccular mucous glands are similar, but the latter 

 react to Delafield's haematoxylin very much like that of the 

 mucous glands of the foot, while the former seem to be like 

 serous glands. The odoriferous glands, in addition to being 

 larger than the mucous glands, are also a little more complex, 

 i.e. compound saccular (PI. 31, figs. 30, 31, Glo). One reason 

 for assigning the odoriferous function to the largest and most 

 numerous of the cutaneous glands is the fact that this species 

 exudes a rather strong odour, which in a previous paper (1921) 

 I have designated as a means of defence, when it is touched, 

 and at the same time mucus secretion is not noticeable. The 

 unicellular mucous glands are typical glands of its kind (PI. 31. 

 fig. 30, Um). The skin of M. vexillifera Bergh (1879a) 

 is also noted for its numerous ' ahnliche Driisenzellen '. 

 And according to Hancock and Embleton (1848 : 103), referring 

 to Aeolidia, ' The outer or dermal layer of the skin appears 

 to secrete the abundant tenacious matter that exudes from the 

 animal, and to be the seat of an exquisite sensibility. This 

 layer is thin but continuous with the next or muscular layer, 

 which might be called the cellular for its structure.' But 

 Flemming (1870) thinks the subepithelial connective tissue in 

 Helix pomatia secretes slime. 



