THE NAUTILUS. 19 
b. No noticeable shell-lobes developed ; mucus pore present. 
c. Shell small, depressed and glassy; lower part of vas 
deferens not enlarged, Genus VITREA. 
ce. Shell larger, smoky ; lower part of vas deferens greatly 
enlarged, Genus OMPHALINA. 
eec. Shell smoky, Vitrina-like ; vas deferens not enlarged, 
Genus VITRINIZONITES. 
bb. Right shell-lobe developed ; no caudal pore, 
Genus VITRINA. 
The positions of the genera Pristiloma and Conulus cannot be 
decided until their genitalia are investigated. The latter may 
prove to belong with Microcystis and Guppya in asub-family Micro- 
cystine, characterized by obsolescence of the sessile spermatheca. 
The Ariophantine are well represented in the Orient by Ariophanta, 
Nesta and other genera. The Zonitine by Zonites (restricted), 
Rhysota, Trochomorpha, etc. Although the grooves above the foot- 
edges are present in all Zonitide, the tail pore is absent in various 
members of each prime division, such as the genera Pecilozonites, 
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 Conchological 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 
NauvTILvs as our official organ, we hope for a brilliant future for 
the Chapter. This little corner of Tor Navritus will ‘always con- 
tain articles from the pen of beginners, as well as from those of more 
advanced students of conchology. 
A DAY ON THE SPOON RIVER IN ILLINOIS. 
Report of Dr. W.S. Strode, Lewistown, Ill. 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 
