35° The Ohio Naturalist. [Vol. V, No. 7, 



Tetmemorus laevis (Kutz.) Ralfs. Forma. 

 Length 210/(: breadth 34 «. Frequent. 



Although froin the measureinents given for this species it would seem 

 to be either nearer T. Brebissonit or T. granulatus, the form is decid- 

 edly nearer that of T. laevis and the cell wall is smooth or very finely 

 punctate. 



Euastrum verrucosum Ehrenb. 



Length I'lii: breadth GS/i: breadth of apical lobe 2S/t: isthums 15//. 

 Very common, a somewhat compressed form of the species. 



Micrasterias Americana (Ehrenb.) Ralfs. Forma. 



Length l-iO/t: breadth 127/(: breadth of apical lobe SO/c breadth of 



isthusm 27/t. Common. 



This is a peculiar form with the apical lobe spreading rapidh' with its 



base deep sunken in the median portion of the semicell and with a 



peculiar arrangement of the teeth of the end lobe. The variations 



were constant in all specimens seen and the typical form did not 



appear. 



Cosmarium pseudopyramidatum Lund. 



Length 37/'.: breadth 28/'.: breadth of isthmus 6.5/(. Common. 



Cosmarium cyclicum Lund. 



Length 45/(: breadth = length: breadth of isthmus 12.5/i. 

 This species is not included by Wolle in his work and is reported by 

 Johnson among his rarities. It seems however, to be a fairly com- 

 mon species in this country as it has turned up in several widely sep- 

 arated localities in material I have examined. In every way the 

 specimens from Youngstown were typical. 



Cosmariuin Turpinii Breb. 



Length 53-58/'.: breadth 47-53/t: breadth of isthmus 12.5-14/(: thick- 

 ness 34/(. Very common at this locality. Wolle speaks of this 

 species as "not rare." It has not yet been recorded from New 

 England, however. 



Cosmariuin Broomei Thwaites. 



Length 32/( : breadth 28/« : breadth of isthmus 9/(. Fairly comnion. 



Cosmarium Amesii sp. nov. 



Length 47,h: breadth 53/(: breadth of isthmus 15/-(. Common. 

 A Cosmanum of the group represented by C. bimiin Nordst., C. 

 speciosmn Lund., etc. End broadly truncated, slightly refuse. Sides 

 of each semicell with ten granules arranged in pairs as are also the 

 granules of the end. From the border these pairs are repeated 

 inward three or four times. The central basal portion of the side of 

 each semi-cell composed of a roughly circular series of granules 

 arranged in seven vertical rows: the central one, the longest, ^\'ith six 

 granules, at each side of this a series of four and the outer four rows 

 each with five granules. The basal angles of the semi-cells are 

 broadly rounded. This species is named for the collector, Mr. Charles 

 B. Ames. 



Staurastrum punctulatum Breb. 



Length 21)/'.: breadth 28/(: breadth of isthmus 7.5/(. Common. 



Staurastrum muticum Breb. 



Breadth o4/i. Occasional. 



In all, twenty-one varieties and fonns were noted in the collection. 

 Boston Societv of Natural Historv. 



