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THE AMERICAN XATUFALIST [Vol. LV 



organs and the muscles, the connective tissues, as well as 

 the blood, are colorless. This characteristic is also 

 common to M. peUucida Bergh, 1904; and M. vexUlifera 

 Bergh, 1880. 



Upon touching the curious-looking animal it gives off 

 a peculiar odor. This is rather strong, and resembles 

 that of oil of bergamot. It is caused by a secretion from 

 small compound saccular glands lying immediately under 

 the ectoderm (Fig. 12). These glands are distributed all 

 over in the external parts of the body : in the body wall, 

 the papillae, under the ectoderm of the exterior part of 

 the hood, and in some cases, under the ectoderm of the 

 foot. None of these glands seem to be present under the 

 ectoderm of the ventral side of the hood. The extent of 

 distribution of the odoriferous glands seems to indicate 

 that they have a definite use and purpose, e.g., that of 

 defense. 



Meckelii, 1838, describes the odor exuded by Tethys 

 leporina as resembling citron, or being rather pleasant. 

 And l^ergh, 1877, says: 



Y(Ui . . . tntcn Tliicit' lui1)c irh ir-eiii! v'ww Spur lieiiicrkt, dagegen 

 {•inen nid.l slm-kcn. rlwa^ hr.nuArreu. ahcr iiichr wesentlieh unbehab- 



Ileclit, 1890, discusses tlie various means of defense pos- 

 sessed by Nudibranchs. Ife mentions protective colora- 

 tion, nematocysts, mucous glands and death feigning. 

 The last will be discussed presently; the first two may 

 only be referred to, as M. leonina possesses no protective 

 coloration, and has no nematocysts as a defensive means. 

 It may, however, be stated that in the aquarium, Melihe 

 leonina became even more transparent than it was when 

 seen in its natural enviroimient. This change of color 

 Avas also observed by Alder and Hancock, 1845, on a num- 

 ber of Nudibranchs kept in ('ai)tivity: "In such cases 

 they generally h^se a unod (I.-.m! of colour and become 

 very transi)arent, " and tli;il coidration is not caused by 

 the color of the food takt-n, luit by the color of the liver 



