THE NAUTILUS. 19 



b. No noticeable sliell-lobes developed ; mucus pore present. 

 c. Shell small, depressed and glassy; lower part of vas 

 defereus not enlarged, Genus VITREA. 



cc. Shell larger, smoky ; lower part of vas deferens greatly 

 enlarged, Genus OMPHALINA. 



ccc. Shell smoky, Vitriim-like ; vas deferens not enlarged, 



Genus VITKINIZONITES. 

 Ib. Right shell-lobe developed ; no caudal pore, 



Genus VITRINA. 



The positions of the genera Pristiloma and Convlus cannot be 

 decided until their genitalia are investigated. The latter may 

 prove to belong with Micrm-i/*ti.< and Guppya in a sub-family Micro- 

 cyxliine, characterized by obsolescence of the sessile spermatheca. 

 The ArlophantincE are well represented in the Orient by Arlojjltantu, 

 Xe&ta and other genera. The Zonitime by Zunites (restricted), 

 Rhysota, Trochomorpha, etc. Although the grooves above the foot- 

 edges are present in all Zonitithe, the tail pore is absent in various 

 members of each prime division, such as the genera Ptecilozonites, 

 Trochomorpha, etc. The greatest defect in our knowledge of Ameri- 

 can forms is in respect to the Zonitoides and Vitrea groups, the 

 shells of which offer no diagnostic genera features ; and the nomen- 

 clature cannot be settled until the presence or absence of a dart- 

 sack is ascertained in all the small species. The animals should be 

 drowned, as ordinary alcoholic specimens of these minute forms are 

 almost impossible to manipulate. 



ISAAC LEA DEPARTMENT. 



[Conducted in the interest of the Isaac Lea Conchotogical Chapter of the Agassiz 

 Association by its General Secretary, Mrs. M. Burton Williamson.] 



The outlook for the Isaac Lea Chapter for this year is very en- 

 couraging; new members are coming in, and all our members are 

 enthusiastic in regard to the possibilities of the Chapter. With THE 

 NAUTILUS as our official organ, we hope for a brilliant future for 

 the Chapter. This little corner of THE NAUTILUS will always con- 

 tain articles from the pen of beginners, as well as from those of more 

 advanced students of coneholouv. 



A DAY ON THE SPOON RIVER IN ILLINOIS. 



Report of Dr. W. S. Strode, Lewist.uvn, 111. From the Transactions of the Isaac 

 Lea Conchological Chapter of the Agassiz Association for 1894. 



Owing to sciatic rheumatism, the writer, during the past summer 

 and fall, has been unable to do much active work in the collecting 



