C^CILIOIDES. 3 



" Eyes and Tentacles. Jeffreys' enlarged figure (Brit. Conch., 

 Vol. I, pi. 7, fig. 19) is not quite accurate. He seems to have 

 taken his description from Nilsson, and it may be doubted 

 whether Jeffreys himself examined the animal with sufficient 

 care. Nilsson had evidently studied the animal, but he was 

 not correct in describing the upper tentacles as ' not thickened.' 

 In all the specimens that I have observed the upper tentacles 

 are certainly slightly bulbous when fully or nearly fully ex- 

 tended, though this does not appear when they are only slightly 

 protruded. Nilsson, however, correctly remarks that the apices 

 of the upper tentacles are not 'marked with a black spot.' 

 Now Lamarck (to whom Nilsson refers) seems to have been the 

 only one to observe the colorless eyeball, and he did not recog- 

 nize them as such. Nilsson says (quoting Lamarck) "In this 

 species no eyes indeed are exposed, unless they are white, like 

 the tentacles themselves. These, indeed, are terminated by a 

 convex surface, very smooth, very shiny, surrounded by a 

 slightly impressed ring; which surface doubtless answers to the 

 eye of other terrestrial mollusks. But this animal, probably 

 because it lives underground, where it cannot use eyes, appears 

 to us plainly to lack eyes.' Now I have noticed that these 

 peculiar convex endings with a constricting ring are in fact eye- 

 balls, and also that they are retractile, but whether they have 

 retained the power of sight in spite of their loss of pigment, I 

 am not prepared to say (see fig. 8>. As far as my observation 

 goes, the animal is insensible to light, though it will crawl 

 straight away to a heap of moss; the direction, however, may 

 be determined by scent alone. If it is deficient in sight it cer- 

 tainly uses its tentacles to all appearance in the same manner as 

 its more favored brethren. I may mention in this connection 

 that an albino specimen of Limax maximus, whose eyeballs were 

 also destitute of pigment, seems to act in a perfectly normal 

 manner. Though my observations on this point (Journal of 

 Conch. , Vol. 9, p. 24) tend to show that this species is lacking 

 in sight, I am not aware to what degree of perfection the vision 

 of terrestrial mollusks attains, but I have noticed that Cydostoma 

 elegans and Helix pomatia seem sensitive to the approach of a 

 large object." (Lionel E. Adams in The Journal of Conchol- 

 Vol. 9, p. 207.) 



