1867.] 



133 



[Stodder. 



From the peculiarities of the place there is no tidal current what- 

 ever, the water only risino; and falling with the tide. Some materials 

 or oi-ganisms may be blown on the surface of the Avater, but other 

 than tliat, all the organisms found may be considered as bein"- in their 

 native habitat. Now Ave have in this locality a deposit of unknown 

 depth, made up essentially of organic matter, more or less decom- 

 posed. The silicious shells of the Diatomaceaj, being indestructible 

 are found abundantly in the superficial mud, and may be expected to 

 bear a still larger proportion to the whole at greater depths. The 

 living diatoms were very numerous, but all being mixed too-ether 

 there could be no attempt to specify which were living and which 

 were dead. 



The variety of diatoms found is very great. The following species 

 have been identified, not, however, in all cases as being exactly like 

 the typical forms, but so nearly as to be within the admitted limits 

 of specific variation. 



Pleurosigma inflatum Shadb. 

 " elongatum. 



" Balticum. 



" fasciola. 



" ffistuarii. 



Stauroneis salina. 

 " aspera. 



Navicula punctulata. 



" lyra — elliptic and aplcu- 



late. 

 " elegans. 

 " Smitbii. 



" didyma, several varieties 

 " granulata Bail. 

 " libellus Greg. 

 " quadrifasciata. 

 " variant Greg. 

 " gastrum. 

 " iridis. 

 " kergulensis. 

 " bombus. 

 " nebulosa. 



" (Pinnularia) perigrina. 

 " " lata. 



Amphora membranacea. 

 " salina. 

 " robusta. 



Nitzschia sigmoidea. 

 " sigma. 

 " scalaris. 

 " plana. 

 Achnanthes bi-evipes. 

 Rhabdonema arcuatum. 

 Fragillaria capucina. 

 Triblionella punctata. 

 Auliscus americanus. 

 Himantidium parallelum. 

 Amphiprora complexa Greg. 

 '' maxima. 



" vitrea. 



Cocconeis placentula. 

 " scutellum. 



Raphoneis ? 



Cymbella Ehrenbergii. 

 " ? 



Eunotia obtusa. 



" tetraodon. 



" Ehrenbergii. 

 Actinoptychus senarius. 

 Triceratium punctatum. 

 Syndendrium diadema. 

 Synedra crystallina. 



" fulgens. 

 Surirella linearis. 



