INDUSTRIAL PROGRESS DURING THE YEAR 1875. clxxxiii 



of Ammonoids, showing that the characteristics of the first 

 three stages of the embryo were inherited from a very early 

 period. These were, first, the sac-like shell of the embryo, 

 containing the equally sac-like beginning of the siphon ; 

 second, the beginning of the true shell or apex, with its 

 nautilus- like septum and peculiar nautilus -like umbilicus; 

 third, the depressed and goniatite-like continuation of the 

 form of the shell, w T ith its accompanying goniatitic septa. 

 These, of course, represent only their most advanced stage 

 in the Ammonites proper of the Jura and Trias ; they are, 

 when first observed in the Silurian and Devonian, exceeding- 

 ly variable in the length of the periods and other important 

 characteristics, even between the varieties of different spe- 

 cies. They become invariable in the young as embryonic 

 characteristics only after the lapse of time represented by 

 the Silurian, Devonian, and Carboniferous periods. This va- 

 riability in the same species in the Silurian shows how re- 

 cently they were inherited, and their invariability in every 

 individual of the Jurassic shows the results of the lono; as;es 

 of inheritance through which the group has passed between 

 that period and the Silurian epoch. 



A number of descriptive papers appear in the Proceedings 

 of the Zoological Society of London, and the German and 

 French conchological journals. Among these, Beddome's 

 "Descriptions of some new Operculated Land -Shells from 

 Southern India and Ceylon," Mr. Guppy's notes on West 

 Indian shells, and descriptions of new shells from Queens- 

 land, by Mr. Brazier, are noteworthy ; while in this country 

 the report on the mollusca of Hayden's Survey of the Ter- 

 ritories, by Mr. E. Ingersoll, gives new information relating 

 to the distribution of land-shells in Colorado. It seems that 

 no land-shells were found on the eastern slope of the Rocky 

 Mountains (though they do exist there). Altitude seemed 

 to have little influence upon their range so long as other 

 favorable conditions were present. The number of species 

 which occurred was very small, owing to the dryness of the 

 country. The Pupce were perhaps the most common forms, 

 increasing southward, while specimens of Vertigo Calif or- 

 nica and Pupilla alticola were numerous every where in the 

 mountains as high up as timber grows. 



Our knowledge of the lower worms has been advanced by 



