46 



b. Specimens illustrating the mode of development of 

 Conularia gracilis Hall (vide. Amer. Geol., Mar. and 

 Aug., 1896, and Report State Geologist, N. Y., 1894 

 [in press]). 



The specimens show that the 3'ounger stages of Conularia 

 gracilis were attached to foreign bodies by basal cup-shaped ap- 

 pendages, and tliat the development began with small conical 

 shells Yz mm. long, which were provided with triangular proc- 

 esses at the aperture. In course of development the marginal 

 grooves appear, by which the shell assumes the four-sided pyra- 

 midal shape of the mature stage. Later also the surface sculp- 

 ture of intersecting transversal and longitudinal ribs becomes 

 noticeable. 



Many of the shells of the middle stages of growth are strongly 

 arcuate. This, as well as the absence of the sides of the pyra- 

 mid between the stronger walls of the marginal grooves, give to 

 many of the fossils an appearance which differs from that of a 

 well-preserved Conularia. Both features are due to a beginning 

 decomposition before fossilization. 



1 1 . Fossil Insects from the Tertiary Deposits at Flor- 

 issant, Colorado. 



Exhibited by Samuel H. Scudder, Cambridge, Mass. 



Florissant has furnished more fossil insects than any 

 other locality in the world (amber localities excepted). 

 The larger number of those found are still undescribed. 

 This exhibit embraces types of a few of the species de- 

 scribed by the exhibitor, with a few still undescribed 

 species. All the principal orders are represented and 

 the specimens have been selected with 'a view to va- 

 riety. Three butterflies are shown, a group of which 

 less than a score of specimens are known to exist. Il- 

 lustrations of some insects from other American localities 

 as well as from Florissant are shown on the plates on 

 the wall. 



LIST OF SPECIES EXHIBITED. 



Arachnida (Spiders). 



8269. Anyphcena i?iterita. 

 1 1 65 1 . Nephila pefzfiatipes. 



Orthoptera. 



13544. Labiduromma avia (Earwig). 



