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IOWA ACADEMY OF SCIENCES. 
each organ opens into the pericardial cavity, and at the other 
end into the cloacal chamber. Fig. 1, o shows the right 
organ as seen from the left or inner side, and Fig. 7 is a dia- 
gram of the left organ as seen from the left or outer side. By 
comparing the two figures the relations of the loops will be seen. 
The cells lining the organ are apparently not glandular in the 
immediate vicinity of the pericardial opening, and are rather 
small near the cloacal opening, but throughout the rest of the 
tube the cells are large and vacuolated, as shown by Fig. 11, 
which represents specially large cells from the dorsal part of 
the organ. I have been unable to find cilia on any of the cells. 
REPRODUCTIVE ORGANS. 
The animal is hermaphroditic. The reproductive organs, 
which are paired, each consist of a racemose gland. Fig. 1, r o, 
situated beneath the pericardium and behind the stomach, 
varying in extent according to the age of the individual, and 
opening into the cloacal chamber close to the cloacal opening 
of the organ of Bojanus. Part of the follicles bear ova, oth- 
ers sperm. The ova- bearing follicles are generally among those 
most posterior. They are fewer in number than the sperm 
follicles, and, in this species, bear comparatively few ova. 
Fig. 8 represents a section of an ova-bearing follicle, in which 
are a number of nearly or quite mature and several very young 
ova. The sperm-bearing follicles are generally full of sperm, 
which lie free in their cavities. Reproduction, apparently, 
goes on during the greater part of the year. 
LITERATURE. 
1. Brooks, W. K. Sensory Clubs or Cordyi of Leodice. Jour, of Morph. 
Vol. X, No. 1. 
2. Kellogg, James L. Contributions to our Knowledge of Lamelli- 
branchiate Mollusks. Bui. U. S. Fish Commission, 1890. 
3. Lang, Arnold. Lehrbuch der Vergleichenden Anatomie. 
4. Lankester, E. Ray. Mollusca. Enc. Britt. 
5. Leydig, Franz. Ueber Cyclas Cornea. Muller’s Archiv., 1855. 
6. Mitsukuri, K. On the Structure and Significance of some Aberrent 
Forms of Lamellibranchiate gills. Quart. Jour. Mic. Sci., Vol. 
XXI, 1881. 
7. Peck, R. H. Gills of Lamellibranchiate Mollusca. Quart. Jour. Mic. 
Sci., Vol. XVII, 1877. 
8. Pelsener, Paul. Contribution a 1 ’etude des Lamellibranches. Arch. 
de Biol., Tome XI, Part 2, 1891. 
9. Rankin, Walter M., Uber das Bojanus’ sche Organ des Teichmuschel. 
Jena, Zeit. Bd. XXIV, 1890. 
10. Zeigler, E. Die Entwickelung von Cyclas cornea Zeit. f. wiss. Zook, 
Bd. XLI. 
