90 THE NAUTILUS. 



importance to separate Opisthosiphon from Rhytidopoma, 

 would also have the same consideration in separating C. un- 

 cinatum from Choanopoma. 



It would also seem that if the breathing tube restricted for 

 Opisthosiphon is of generic importance that the modified per- 

 foration seen in so many of the Ericiidae from western Cuba 

 should also be considered of value generically. This would 

 mean, providing that the operculum was still considered of 

 generic value, the removal of species of Choanopoma, of Cistula 

 and of a large number of Chondropoma to new genera. 



This would merely be substituting chaos for confusion and, 

 until the anatomy of many of the species has been carefully ex- 

 amined, it would seem better to merely call attention to the 

 peculiarly restricted distribution of those species of the Ericiidae, 

 which have made structural changes in the shell, probably, as 

 Dr. Ball suggests (Proc. Mai. Soc. Lond., 1905, p. 309) to en- 

 able them to obtain air when the aperture is closed by the 

 operculum. 



SOME MARINE MOLLUSCA ABOUT NEW YORK CITY. 



BY ARTHUR JACOT. 



To aid any New-Yorkers interested in the shells of their 

 vicinity, I am taking this opportunity of giving them the re- 

 sults of a few studies which were made during the past year 

 in that region. 



The coast of Staten Island from Fort Wadsworth to Great 

 Kills was carefully gone over at low tide several times. Along 

 this strip are three definite stations. The first (1) is an ex- 

 panse of red sand flats (exposed only at low tide) at the 

 mouth of the stream, which drains the marshland between 

 South and Midland Beaches. This is the only place where 

 I found Periploma leanum, Pandora gouldiana and Lyonsia 

 hyalina. Another station (2) opposite the Oakwood Heights 

 station on the steam railroad to Tottenville, is a "sod-bank" 

 formation, beautifully sli owing the encroachment of the sea on 



