ZOOLOGY. 781 



to the family named Truncatellidae, and they have been generally asso- 

 ciated with the Cyclostomids and allied animals and considered to be 

 true air-breathing and lung-bearing gastrojiods. The correctness of 

 this view however was long ago challenged, and its incorrectness 

 has been shown during the past year by Dr. A. Yayssiere. The 

 study of the respiratory apparatus of the animal reveals the fact that 

 it is a true gill or branchia, which is placed transversely to the longitu- 

 dinal axis of the bodj^; has itself an elongated form and is composed of 

 twelve to fifteen triangular lamellae, arranged in a row, but each almost 

 entirely independent of its fellows. On the surface of the lamellae, and 

 especially toward the free extremity, there are vibratile ciliae which deter- 

 mine the movements of the water around the organ. It is, therefore, 

 says Dr. Yayssiere, undeniable that the respiration of the animal is by 

 means of branchiae. The mollusk lives in a moist atmosphere, although 

 not in the water, and therefore it keeps stored up in its respiratory cavity 

 a certain amount of water which is renewed every time that the tides 

 cover its station. Dr. Vaysseire adds some details on the habits of 

 individuals kept in confinement. They had been found on the sea bor- 

 der more or less ensconced in the mnddy ooze and in the midst of debris 

 cast on the shore, consisting largely of decaying fruit and animals. The 

 Truncatellas did not appear to be at all affected by the odor of the decay- 

 ing matter. They could remain out of the water and in an atmosphere 

 saturated with the vapor, and could live many days without suffering, 

 but moisture was necessary and they soon succumbed to dryness. Their 

 progress is peculiar, and the movements of the animal recall those of 

 the geometrical caterpillars. ISTormaUy and when in the water it uses 

 only its foot in walking, and does not employ its proboscis save in ex- 

 ceptional cases, and when a special demand is made upon its strength, 

 as when it is creeping upon a vertical and smooth surface, such as the 

 sides of a glass globe. Previous observers, who stated that it always 

 uses its proboscis, were misled by the fact that the mollusk, in its prog- 

 ress (which resembles that of the geometrical caterpillars), performs 

 with the anterior part of its body (the j)roboscis) a certain looping move- 

 ment. This movement, which at the same time entails an approach of 

 the extremity of the proboscis to the ground, leads one to sui)pose that 

 this plays a role in its progress, and one is the more disposed to 

 believe this, as the mouth, which is at the extremity of the i)roboscis, has 

 very much the appearance of a sucker. 



The food of the little animal is chiefly composed of microscopic ani- 

 malcules (such as Infusorians, Amcebas, Foraminifers, &c.), as well as 

 the decomposing remains of algae and other aquatic plants. {Journ. 

 deConchyl. (3) v. 25, pp. 255-288, pi. 12, 13.) 



North American Land iSlugs and Shells. — The terrestrial Gastropods of 

 North America, north of Mexico, which have been treated of to such 

 an extent by Mr. W. G. Binney, have been submitted to a renewed ex- 



