INDUSTRIAL TROGRESS DURING THE YEAR 1876. clix 



Professor Hall for a genus of brachiopods, the name Eatoniella is 

 substituted. Mr. Dall also describes a genus allied to Cerojms of the 

 Carditidce, giving it the name Kidderia^ in honor of the naturalist of 

 the expedition. A new genus of chitons is described by Dr. P. P. 

 Carpenter under the name Hemiarthrum. 



Mr. W. H. Dall describes the way in which the eggs are set free 

 from the ovisac and cavity of the body of the limpets, in which no 

 opening could be found. The minute size and fragility of all the 

 parts was one obstacle. Not long ago, however, Mr. Dall had an 

 opportunity to dissect several limpets of extraordinary size which 

 Professor Agassiz brought home from the Hassler expedition, and 

 found one in which the ovaries were full of eggs. He has observed 

 that those eggs which lay at the extremities of the ovisac nearest 

 the renal sacs were granulated, congested, and much riper than 

 the rest, and that very minute orifices allowed of communicntion be- 

 tween the ovisac and the renal sac. Further examination showed 

 still riper eggs in the renal sac itself, and, as it were, drifting to- 

 ward the external opening, through which they passed into the 

 sea-water. 



The Academy of Sciences has received from M. P. Fischer a paper 

 on the hypsometric distribution of mollusca that is, the altitudes at 

 which they are found. It is a striking fact, says Galignani, that 

 plants thrive on mountains with great regularity, each at a certain 

 height. Every species has its peculiar habitat, and if the mount- 

 ain exceeds 8000 or 9000 feet, vegetable life gradually disappears 

 near the summit. The terrestrial mollusca, being unprovided w^ith 

 means of locomotion enjoyed by birds and insects, and being, more- 

 over, dependent upon vegetable life for food, could not, our author 

 thinks, fail to be distributed in the same way as plants, and this 

 supposition is confirmed by observation. Each species extends to 

 an altitude the limits of which it does not overstep. ]M. Fischer has 

 verified this in the Central Pyrenees as well as in the Alps, and di- 

 vided the altitudes into five zones, comprised between 1500 and 7500 

 feet. Each zone is distinguished by the name of a species of Helix. 

 Thus in the Pyrenees the first zone, ending at a height of 3000 feet, 

 is called that of Helix carthusiana; the second, ending at 3600 feet, 

 H. mperm; the tliird, terminating at 4500 feet, H. limhata; the fourth, 

 limited at GOOO feet, H. nemoralis; and the fifth, ending at 7500 feet, 

 //. carascalensis. In the Alps, at the same altitudes, the names of the 

 zones are respectively Helix cartJitisiana, ohvoluta, Fontenelli^ sylvatica, 

 and glncialis. A few individual mollusks may, indeed, climb as high as 

 9000 feet, but they will stop at the limit of perpetual snow. Various 

 genera of fluviatile molUisks do not ascend higher tlian 3000 feet a 

 circumstance of some importance to geologists, since it proves that 

 in the quaternary beds the fossiliferous strata containing those gen- 

 era, such as Neritifia, etc., were deposited at small altitudes. 



