1893.] 



MICROSCOPICAL JOUIIXAL. 



47 



pool aiul ditches tartlicr froiii salt water and iiKJie nearly fresh 

 occasioiiallv contain /'. (crryanuni. sonietinies mixed witli /'. 

 balticnnis hut frequentlv entirely pure. P. amcricaniitn is found 

 chieilv in the waters oi tidal creeks, and P. decorum and the 

 smaller form of /'. halticiitn in the more saline ami deeper 

 waters of coves and havs. The native hahitat of Actinocyclus 

 barklexi is on the hottcjm of the larjjer tidal creeks, or in ditches 

 and marshes of an estuary of a fresh- water river. 



The tide-pools in the marshes on the banks of Branford river 

 are verv rich in P. balticum,, and some of them contain P. 

 augulatiini . Siirirclla striatula and the larger sij^moid 

 Nitzschia are also abundant. The fossil deposit of diatoma- 

 ceous clav underlying tiiesc marshes I have had but little oppor- 

 tunity to examine, as no excavations have been made. It diHbrs 

 from the others described, in that tiie upper layer just below the 

 peat contains abundance of Canipvlodiscus cclicneis^ so that 

 slitles can be made tVom it in which the Campylodiscus is 

 entirelv pure. The stratum just below this is very rich in 

 species, somewhat rcsemblinj^ the Leete's island deposit. Dr. 

 D. B. Ward sends me the following determination of the forms 

 in a single slide from this stratum of the deposit which I sent 

 liini. marked No. i. B : 



Coscinodiscus excentricus. 

 " ociihis iridis. 



" siibtilis. 



" raiiiatus. 



Scoliopleura tiiinida (abundant). 

 Nitzschia acuminata. 

 " sigma. 

 " elongata. 



" plana (and several others). 

 Actinoptvclnis undulata. 

 Tryblionella hantscliiana. 



punctata. 

 Cvclotella striata. 

 Rhabdonema adriaticum. 

 Surireila febegerii. 

 striatula. 

 " fastuosa var. 

 Coconeis scutellum. 

 Melosira sulcatum. 



Pleurosigma balticum. 

 " affine. 



" formosuni. 



Navicula forniosa. 

 " marina. 



'■ fonnosa var. hiburnica. 



erucicula. 

 elliptica. 

 peregrina. 

 oblonga. 

 lyra. 



inlerrupta. 

 digita radiata. 

 Campylodiscus ecbeneis. 

 Pyxilla baltica. 

 Tropidoneis seriata. 

 Raphoneis amphiceros. 

 Plagiograinma gregorii. 

 Amphiprora conspicua. 



Stauroneis gregoni. 



He adds : ".There are several Nitzschias and AntpJwras 

 which I did not look up." 



The stratum next below this is of liner clay, containing mostly 

 lighter varieties, with many species of Pleurosigma. 



Dr. Ward determines two of the forms to which I called his 

 attention as : '* Tricenttium {ditylunn)brigJit'j.'eUii \ViX. iriae- 

 qualis Grun. = Dltyliutn inaeqiiale Bail. 



'^Navicula ( V^an Heurckia) rJiomboides var. amphipleu- 

 roidcs Grun. Cleve & Grunow, Arctic Diatoms, PI. iii, f. 59." 



I have so far examined only the three uppermost layers of the 



