1895.] MICROSCOPICAL JOURNAL. 43 



salina, one being tlie same size as those previously found, 

 the other considerably larger. Stauroneis salina is com- 

 mon all along the Connecticut shore, but I have never pre- 

 viously found them abundant in any one gathering. The 

 common form is many times larger than these in this liv- 

 ing film. Parts of this film now showed large numbers 

 of Pleurosigma, — P. fasciola, P. affine, P. angulatum, P. 

 decorum, and P. balticum being abundant. 



Crossing over Leete's Island, I found Great Harbor 

 Beach showing only a few patches of brow^n film from 

 six to ten feet in diameter. These were generally sim- 

 ilar to that on Shell Beach, but on the north side of the 

 harbor I found one in which Pleurosigma fasciola was 

 accompanied by an equal number of a form I had never 

 before seen. This was cylindrical and straight, both ends 

 tapering down to a hyaline prolongation which was tip- 

 ped with a small knob. By holding a frustule of P. 

 fasciola so as to give an edge view with a linear outline, 

 it closely resembled the new kind but was only about 

 two-thirds as large. Both were very active, swimming 

 about with ceaseless activity, and at about the same rate 

 of speed. The new kind proved to be destitute of silex, 

 being completely dissolved by acids. 



Two weeks later the sheet of living diatoms still cov- 

 ered the mud at Shell Beach at low tide. It was now 

 composed chiefly of the larger Stauroneis with Pleuro- 

 sigma in greater abundance, and was of sufficient thick- 

 ness to be separated from the mud aud rolled up into 

 floating masses by the advancing tide ; two months later, 

 in September, the brown fllm had entirely disappeared, 

 low tide showing only a broad expanse of soft mud. 



West of the depot at Branford, a new bridge had been 

 built. In digging for the foundations a large amount of 

 marine deposit had been thrown up which all contained 

 diatoms. Part of it was quite similar to the upper 

 stratum at Leete's Island which showed Navicula didy-, 



