76 THE NAUTILUS. 



mentioned in the Bull. No. 9 of the Boston Society of Natural 

 History, April, 1917, where the exact size, lOf in greatest 

 diameter was given, as there was a discrepancy of If 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. 



In 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 8f by 11 inches. I am in- 

 debted to Mr. Arthur Jacot for these measurements. 



SOME AUBICULIDAS AND PLANOEBIDAE FEOM PANAMA. 



BY HEJSfRY 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 

 whorl above the middle. Aperture extreme!}' narrow, having a 



