6234 



Marine Aquarium . 



position as the head of Rissoa,- — it is narrower than, and carried in 

 advance of, the foot. Clark, and Gray after him, call the men turn 

 the head ; but, as the former himself says the proboscis issues under 

 the tentacles and above the mentum, it does not seem likely that it 

 really is so. I have never seen the proboscis exserted. 



Capulus hungaricus, contrary to what might be expected from its 

 Sedentary habits, could move for 'a few inches even on the smooth 

 erect sides of a glass jar. The proboscis or rostrum (like that of 

 Cypraea, it seems to be of an intermediate character) is capable of 

 extension, and can be produced beyond the shell. I have not 

 succeeded in preserving it for any length of time. Like most of its 

 relatives, its habits and food are very imperfectly understood. 



Hydrobia Ulvse. It is difficult to place much confidence in 

 drawings of animals of the Mollusca, when we find this common and 

 easily -observed mollusk most incorrectly represented, both in the 

 ' British Mollusca' and in the * Genera of Shells.' Besides incorrect- 

 ness of proportion, which it is not easy to specify with accuracy, 

 both Forbes and A. Adams have made the foot triangular and 

 pointed behind, instead of oblong and obtusely rounded; they also 

 make the opercular lobe narrower than the foot, instead of extending 

 over the sides as in Bithinia. Adams has also given the rostrum a 

 curious twist upwards. The emargination of the rostrum is caused 

 by the retraction of the buccal mass, and disappears when it is 

 applied to any surface ; it then has a slightly globular or inflated 

 appearance. In the text of the ^British Mollusca' the foot is cor- 

 rectly described. There is a distinct marginal groove across the 

 front edge of the foot, which does not extend quite to the tips of the 

 auricles. The foot is thus bilabiate, or provided with a linear dupli- 

 cation as in Littorina. There is a curious and easily observable 

 process or fillet issuing from the anal angle of the aperture, the use 

 of which is unknown. The male organ is in the usual place, falcate, 

 compressed, lead-blue sprinkled with yellow. The foecal pellets are 

 oval, brown, often clustered ; they have not bred in confinement, 

 though they grow to a very large size, some being as much as one- 

 third of an inch in length. Clean specimens have the shells 

 chestnut-brown, lighter near the sutures. When taken on the shore 

 they are of a dark brownish green, and hardly half of the size they 

 attain in confinement. The young have the shell more or less trans- 

 lucent, and the animal colourless ; the black bars on the tentacles 

 appear first as a sprinkling of black dots. The buccal mass is, 



