DociDitTM. 53 



what larger, and often granulate; apices crowned with a few 

 prominent teeth, usually three in view. 



I tiameter 12-13 //. 



Pleasanl Mills, Brown'- Mills, etc. New Jersey. 

 The inflation at the base of the semi-cells is more promi- 

 nent than is usual in D. minutum. 



I), oosi \tim. Wblle. Plate X. fig. 2. 



Fusiform, 78 times longer than broad ; slightly constricted 

 in middle; inflated gradually from the base of the semi-cell to 

 about one-third the length, then gradually tapering to the 

 truncated, slightly dilated and dentate apes ; margins with 

 regular crenae, produced by twenty or more distinct transverse 

 costae or rib-like lines. 



Diameter, widesl pari 25 ., constriction 20 ., ends 1517 u. 



Pound by H. I). Kitchel in pond, Berkshire Mountains, 

 Massachusetts, 1882 



The specimens which eame under my observation were not 

 \ i _ r etativ t Id ; this species need- verification. 



1 >. verth ii. i. a 1 1 m. [Triplooeras ViaiieiUatum t ) Bail. Plate X. 

 figs. 1.11. 

 Cells large subcylindrical, with numerous whorls of small, 

 oblong, often tooth-like prominences ; 7 16 times longer than 

 broad ; end- with three bidentate diverging proci s 3. 

 I liameter ordinarily 38 15 u. 



Var. TXTRGIDl If, fig. Ill, Wolle. Shorter and -t outer, often 60 ,". 



Of frequenl occurrence in |>ond water-. Maine to Florida. 



The Dumber of whorls varies from 12-16 in a semi-cell. 

 In living condition the cells are green, but more commonly 

 they are found of brownish red color. 



J), qbacile, i Triploceras graeile,} Bail. Plate X, figs. 3, 6, 7, 8. 

 Differs from the last in usual -mailer -ize of cell, -mailer 

 and more acute tooth-like prominences of the whorl-. 



Diameter 20-28 fi., exceptions, up to 40 >/.. 



Habitat the same as the former. 



The whorls appear to be composed of a double series of 

 teeth, but frequently the second row is barely evident. Fig. 3 

 is of unusual size. Fig. 7 represents a condition of dissolu- 



/ 



