78 DESMIDS OF THE UNITED STATES. 



side ; lateral view circular, with two inconspicuous granules 

 on opposite sides ; membrane punctate. Isthmus about one- 

 third of the diameter. 

 Diameter 30 //. 



Brown's Mills, New Jersey, is the only locality which has 

 hitherto furnished this form. The original, found in Brazil, 

 differs somewhat in the "sinulineari, extrorsum vixampliato." 

 Our form has the sinus decidedly enlarged towards the 

 mouth. 



G. von Lagerheim appears to give too much prominence 

 to simple differentiations mere vagaries of the same species. 

 They may be briefly noted. 



1. C. taxichondrum, var. bidentulum, as above. 



2. C. pseudotaxichondrum, cells more depressed. 



3. (7. pseudotaxichondrum^ var. trichondrum, semi-cells ornate 

 with a single row of three granules. 



4. C. pseudotaxichondi*um, var. quadridentulum; in front view, 

 the inferior angles bidenticulate. 



5. 0. pileigerum. Merely a depauperated form of the above. 



Pond, Tewksbury, Massachusetts. 



C. ANISOCHONDRUM, Nord. Plate XIX, figs. 43-45. 



Cells subquadrate, length and breadth nearly equal ; sinus, 

 narrow linear ; semi-cells subsemicircular, dorsum broadly 

 truncate ; in center two horizontal rows of large granules of 

 three each, and two intermediate granules below and above ; 

 smaller granules, more scattered on each side ; viewed from 

 the vertex, elliptic, with three larger granules on each side 

 and a number of smaller ones within the margin ; the middle 

 bare ; lateral view obovate, circular. Isthmus one-third the 

 diameter of cell. 



Diameter 30-38 ^. 



Denmark Pond and other ponds of northern New Jersey. 

 The original of this species was collected on the Sandwich 

 Islands and described by Dr. Nordstedt. 



C. QUINARIUM, Lund. Plate XLIX, figs. 10, 11. 



Cells subhexagonal, about one-fourth longer than broad ; 

 constriction deep linear ; semi-cells subtrapezoid, narrowed 

 toward the subtruncate apex, sides somewhat convex, infe- 

 rior angles obtuse, margins obsolete granulate-dentate ; 

 within the margin a series of prominent granules, in center 

 five obtuse granules arranged in two transverse series ; 



