|]0 FESTSKRIFT FÖR LILLJEBORG 14 



In the interior of the lenticular body I have not with certainty observed 

 any nerves, although certain fine fibrils might be supposed to be such. But in the 

 lateral sections just outside the lenticular body I have seen large nerves transversally 

 and obliquely cut of the same thickness as the largest arteries, which were directed 

 towards the lenticular body and probably innerved the same. There is more than 

 one such nerve but whether they all go to the "terminal papilla" or not I cannot 

 bay. Where the nerve is obliquely cut, one can see a fine fibrillous structure and 

 a few long cylindrical nuclei probably belonging to the neurilem. The nerve is en- 

 closed in a sheath of connective tissue. 



The inner surface of the terminal disk nearest to the shell is covered like 

 that of the pallium, by a rather well preserved low epithelium with flat depressed 

 darkly stained nuclei. These cellules do not seem to have any secretory function 

 nor to partake in the formation of the shell. 



The longitudinal muscles of the pallium do not reach further than to the 

 plaee where the pallium passes over into the thickened terminal disk. There they 

 insert themselves in the connective tissue. 



Although the above, given description is not so complete as could be de- 

 sired, some conclusions can nevertheless be drawn. 1) The "aboral fossa" and the 

 "terminal papilla" constitute a comparatively large and well developed organ which 

 is richly nourished by bloodvessels and well innerved; thus it cannot be a mere ru- 

 diment or a reduced organ; it seems much rather to be of great importance to the 

 animal. 2) The structure indicates that it cannot possibly be either a gland or an 

 adhesive apparatus. 3) The "terminal papilla" is also with its outer gelatinous cover 

 and inner cellular lenticular body by far too tender to serve as a buffer or protec- 

 tive apparatus, when the animal swims backwards. If it were anything of that kind 

 we should expect to find a firm connective tissue with a dense and a, most probably, 

 fibrous intercellular substance with comparatively few cellules and small nuclei, which 

 however is far from being the case. In three different places we find the tissues 

 modified for some purpose: 1) the "hemichondroid" lamella, to make the lip elastic, 

 2) tin gelatinous layer on top of the papilla, and 3) the cellular tissue of the lenticu- 

 lar body. But the question of the function is still unsolved; nor does it admit of so- 

 lution with absolute certainty until material sufficiently well preserved for histological 

 r< search is obtained. I do not think however that I shall be far wrong in assuming 

 this organ to have a sensory function; many points support that interpretation. Thus 

 for instance, its situation in a groove protected by stiff and elastic lips, its rich vas- 

 cularization and innervation, its tender tissues, and absence of chromatophorcs in its 

 ntral parts, although they are present in the peripheric. As the epithelium is 



