44 THE AMERICAN MONTHLY [Feb., 



mus and related varieties, another part showed Surirella 

 febegerii with numerous other varieties which were 

 shown by the twelve foot stratum at Leete's Island. 

 Much of this marine deposit is not rich, but it all con- 

 tains diatoms. Silver Sands is a watering pilace about 

 two miles east of Light House Point at the entrance of 

 New Haven Harbor. Between these two places stretches 

 a salt marsh divided from the waters of the Sound by a 

 bank of sand thrown up by the sea, which I should judge 

 to be from two to five hundred feet wide, and several 

 feet higher than high tide. 



The waters of the marsh communicate with the Sound 

 by means of Morris Creek near Light House Point and 

 two small creeks at Silver Sands. I procured material 

 from the marine deposit underlying this marsh at several 

 points, and found it contained diatoms in most respects 

 similar to those of the deposit at Leete's Island, but 

 with some differences. Instead of the Navicula maculata 

 so plentiful at Leete's Island but which was very rare 

 here, it had many more specimens of Navicula latissima 

 and related varieties. Cerataulus polymorphus and C. 

 turgidus, with Biddulphia pulchella were much more 

 abundant and varieties of Auliscus were also more plen- 

 tiful. 



At about four or five feet from the surface 1 found 

 a stratum containing rather more numerous varieties 

 then any previously described in which were mingled 

 both deep and shallow water kinds. The upper stratum 

 in all these marshes that is penetrated by the roots of 

 sedges and other marsh plants, nearly always contains 

 numerous varieties of Navicula constricta or Diploneis, 

 and also many varieties of Navicula elliptica. Below this 

 are strata with Pleurosigma and Campylodiscus, then 

 comes Coscinodiscus and Actinoptychus. The strata 

 sometimes alternate so that shallow water kinds are 

 found below those containing only deep water varieties. 



