GAST3ROPODS 333 



EYES 



In Fnlgur the eyes are situated near the bases and upon the 

 outer sides of the tentacles ; in Buccinum they are extremely small 

 and are mounted about midway between the bases and the tips of 

 the tentacles. This is the usual position for the eyes in the 

 marine Gasteropoda. Only in the pulmonates, or land-snails, are 

 the eyes placed at the summit of the tentacles. Sight does not 

 appear to be a very important sense in the gasteropods, although 

 the eye in some instances becomes a highly developed organ. A 

 number of forms that have the habit of burrowing deep into the 

 sand or mud are quite destitute of visual organs, and certain 

 cave-dwelling land-shells have entirely lost the sense of vision. 



MOUTH AND PROBOSCIS 



The mouth will easily be seen in both Fulgur and Buccinum. 

 It is a small slit with slightly thickened, fleshy lips, and is placed 

 on the lower forward portion of the head. In the case of both 

 of these genera the mouth is situated at the end of a proboscis. 

 It will be noted that Fulgiir has a comparatively long and stout 

 proboscis, or snout, which is not retractile. Buccinum has a smaller 

 one. It is fairly safe to assume that all gasteropods that possess 

 a proboscis are carnivorous. This organ is greatly developed in 

 some genera, where it actually exceeds in length the rest of the 

 animal. In such instances, no doubt, the creature is enabled to 

 reach the interior portions of the shells of its victims and to 

 devour every vestige of their flesh, for the mouth is most con- 

 veniently placed just at the end of this long, trunk-like organ. 

 The genera which have no proboscis are, almost without excep- 

 tion, vegetable feeders. 



We must now remove the animal from its shell. It is well to 

 boil it first, for this does away with the annoying mucous secre- 

 tion that is freely exuded by glands in the foot when the creature 

 is roughly handled. Alcoholic specimens are apt to be much 

 contracted and hardened, and are therefore less satisfactory as 

 subjects for anatomical study. If it is not convenient to boil the 



