Navicnlacea.'] infusorial animalcules. 417 



PiNNULARiA amphijomphits. — Largci-, oblong dorsally, sidi's 

 plane, ends acutely wedge-shape ; it is remarkable by indistinct 

 longitudiual lines ; approacbes Navicida amj)hi(/omj?hus. 



P. amj)luoxys. — Narrow, linear lanceolate, acute; sides with 

 straight pinnules. New York and Iceland. 



P. amphiprora. — Larger on back, narrowly lanceolate, ends broad, 

 obtuse ; it has the habit of Ainphiprora Navicida, but with marginal 

 apertures at the extremities. Massachusetts. 



p. Apis. — Oblong on the back, and so much constiicted at the cen- 

 tre, as to be nearly cUvided into two sub-oi'bicular segments ; ends 

 obtuse, pinnules rough (granules), and twelve in l-1200th. Vera 

 Cruz. 



P. horealis. — Striated, small, laterally linear, ends rounded, but 

 not constricted; pinnules strong. Has the habit of Fragilaria 

 pinnata. ChiH, New York. 



P. chilensis. — Larger, oblong, straight to the sides ; ends broadly 

 rounded, not constricted ; pinnules strong, and eleven to twelve in 

 1- 1200th; approaches P. wr/i/s, but is shorter and broader. Chili. 

 (P. 15, f. 33.) 



P. (?) Conops. — Oblong on back; divided into two cordate 

 parts by a central constriction ; ends apiculate ; pinnules very 

 minute. Vera Cruz. 



P. costata. — Large, thick, short, ovate, oblong; ends Avidely 

 rounded; pinnules large, prominently costate, six in l-1200th; 

 approaches P. Dacfi/Ius. North America. 



P. Cyprianus. — Oblong-lanceolate, ends widely rounded, umbilicus 

 oblong. Chili. 



P. Dacti/lus. — Long, bacillar, straight laterally ; dorsally very slightly 

 curved toAvards the extremities, which are broadly rounded ; pinnules 

 fourteen in 1-1 200th. North America. 



P. decurrem. — Stiiated, narrow, elongate, lanceolate ; dorsally 

 broad, and tiimid at centre^ somewhat narrowing towards the extre- 

 mities, which are however widely roimded ; approaches P. gibba and 

 = P. Trabecula, a smaller variety. 



P. dwiiiphala. — Short, broadly lanceolate on back, ends constricted, 



