82 THE AMERICAN MONTHLY [Mar., 



dreds where the other has one. To Dr. Ward's list above 

 I would add " Namcula theta, CI. n. sp." Pleurosigma 

 suhsalinum and simile, " Gyrosigma tempereiV' CI. n. sp. 

 i explored Pine Orchard Creek but found only the usual 

 kinds. Pleurosigma americajium is found in all the tidal 

 creeks I have so far examined. The rail road crosses 

 the head waters of this creek and the pressure of the new 

 enbankment has thrown up the earth on each side but 

 has not exposed the deposit. I dug down in one of the 

 largest cracks and procured earth from about seven feet 

 below the surface, but found the deposit to consist en- 

 tirely of fresh water diatoms. Stauroneis baileyi, Pin- 

 nularia lata and Namcula americanu were characteristic 

 forms. 



Rodger's Creek. near Leete's Island Depot is rich in 

 Pleurosigrna, containing nearly all the common kinds, 

 with abundant Nitzschia and Synedra and very large Jtfe- 

 losira borreri. I took material from the numerous pond 

 holes in the marsh, but have not yet found anything new 

 in them and have given them only slight examination. 

 The deposit underlying the marsh contains similar forms 

 to the other Leete's Island deposits, but has not yet been 

 carefully studied. From the shore to the Depot at 

 Sachem's Head, a long cove extends about a mile in 

 length, and is called " Long Cove." This contains Pleuro- 

 sigma. terryanum, Namcula maculata and N. perinagna. 

 The pond holes in the marsh at Sachem's Head are very 

 rich in Pleurosig7na balticum var. rnaxime ; they are near 

 the salt water, and I find that shallow salt pools often 

 contain P. balticum., those farther back and more brack- 

 ish are likely to have P. elongatum, while those very 

 nearly fresh have sometimes terryanum. 



Here I would like to give a caution to collectors; the 

 material from such pond holes and tide pools has usually 

 very little sand, but is chiefly composed of organic mat- 

 ter; this becomes quite firm before it is anywhere near 



