182 THE CHICAGO ACADEMY OF SCIENCES. 
the vaginal opening, the two organs forming the short vagina; albu- 
miniparous gland large, oval, very tightly bound down to the oviduct; 
first accessory albuminiparous gland very large, embracing the oviduct ; 
second accessory albuminiparous gland small, round, attached to the 
oviduct a very short distance above the first albuminiparous gland. 
The organs are colored as follows: Albuminiparous gland bright 
yellow, prostate black shading into dirty white, oviduct yellowish or 
dirty white, receptaculum seminis flesh-colored on its lower part, bright 
orange on its upper part; penis-sac yellowish; the other organs white. 
The measurements of the genitalia may be tabulated as follows: 
Rec. sem. Prostate Penis-sac Penis 
Penis. Penis-sac. duct. duct. Vas. def. retractor. retractor. Shell. 
7.50 6.00 6.50 6.50 17.00 2.10 Bele 29.00 
9.00 6.00 6.00 5.50 15.00 4.50 5.00 31.00 
9.00 ° 7.00 6.00 7.00 15.00 4.50 5.00 31.50 
The penis-sac retractor is peculiar (pl. XII, fig. F); for about 
half of its length it is a narrow band of muscle; at this point it sud- 
denly enlarges, forming a thick pad-like structure, which bifurcates 
unequally, continuing to the penis-sac in two wide, flat bands of muscle, 
which enter the penis-sac by several branches. (Dissection No. 23085 
and 23086. ) 
The genitalia of the Lincoln Park auricularia is similar to Eisig’s 
figure (Zeitsch. Wissen. Zool., XIX, p. 29), the organs, however, not 
being shown in much detail in his figure, but their relative shapes are 
similar. Moquin-Tandon’s figure (Hist. Nat. Mol. Ter. Fluv. Fr.) 
shows the organs apparently as in their natural position and the female 
organs as they appear when swollen with water. None of these figures 
show the male organs and their muscles in a clearly defined manner. 
RANGE: Europe and northern Asia; North America (introduced). 
Recorps: Lincoln Park, Chicago, Ills., in greenhouse (Baker); Flatbush, 
3rooklyn, N. Y. (Call; Smith). 
GEOLOGICAL RANGE: Not recorded. 
Ecorocy: <Auricularia is a mollusk which prefers slow-moving 
bodies of water like lakes, ponds and the still parts of rivers. In cap- 
tivity it remains near the bottom of the aquarium, rarely coming to 
the surface. It is rather active, moving about the aquarium with a 
steady gliding motion. 
Remarks: The specimens of auricularia from the greenhouse in 
Lincoln Park seem typical, though some old specimens approach var. 
wentricosa Hartm. The old specimens differ greatly from the half- 
grown ones, the outer lip widely expanding and forming a peculiar 
extension of the aperture at its posterior end, like a rude canal. Some 
specimens recall Radix ampla Hartm. 
