76 THE NAUTILUS. 
mentioned in the Bull. No. 9 of the Boston Society of Natural 
History, April, 1917, where the exact size, 10% in greatest 
diameter was given, as there was a discrepancy of 1}? inches in 
the two accounts in the Proceedings. The writer is indebted to 
the Society for the use of the figure illustrating this article. 
In regard to the nomenclature, it seems hardly necessary to 
enter into any discussion when we consider that we are not 
dealing with a true shell, but a shell-like structure confined to 
the female, and only in part a secretion of the mantle, for a por- 
tion of it is formed by the two expanded tentacles. Internal 
partitions are lacking and the structure serves as a nest for the 
eggs. Tryon, in the Manual of Conchology, places the Indo- 
Pacific A. compressa Blainville (A. maxima Gualt.) in the syn- 
onymy under A. argo Linn., of the Mediterranean. In the 
absence of a thorough knowledge of the animals it seems best 
to keep the various forms described from distant regions sepa- 
rate until such time as future investigations prove them to be 
either the same or distinct. 
{n this connection I would like to call the attention of readers 
to a rival of the above specimen. It is a very large example of 
Argonauta nodosa Solander, in the American Museum of Natural 
History, New York, and measures 82 by 11 inches. I am in- 
debted to Mr. Arthur Jacot for these measurements. 
SOME AURICULIDAE AND PLANORBIDAE FROM PANAMA. 
BY HENRY A. PILSBRY. 
The Panamic fauna has a particularly rich and interesting — 
group of Auriculidae. The following new forms were found 
among the species collected by Mr. James Zetek. 
DETRACIA ZETEKI, n. sp. Figs. a, b, c. 
The shell is oval with short, almost straightly conic spire and 
minute, mucronate apex; dusky buff, the spire, a band near 
the suture and another near the base, carob brown. Surface 
glossy, rather closely marked with ripples of growth. Whorls 
of the spire narrow and flat, the greatest convexity of the last 
whor! above the middle. Aperture extremely narrow, having a 
se eed Ce ee 
aol 
