Naviculacea.} infusokial animalcules. 419 



PiNNTiLARiA 7iobilis. — Yd'y large, striated, of an elongated, quad- 

 rangular, bacillai- figure ; turgid at the centre, and slightly so at the 

 extremities. Length l-84th. Pinnules sixteen to eighteen in 

 l-l'iOOth. Fossil in South America. Terminal apertures very large. 

 San Fiore, Cayenne, Brazil. 



P. pachyptera. — Striated, large, oblong, bacillar, but short and 

 thick ; gibbous in centre of dorsum broadly rounded, not const:"icted 

 at extremities. Pinnules very strong, six in l-1200th. Labrador. 



P. peregrina. — Striated, linear lanceolate, narrow, ends gradually 

 tapering, acute, not constiicted ; pinnules oblique. St. Domingo, 

 Cuba, New York. 



P. pisciculiis. — Striated, very delicate ; narrowly linear ; ends con- 

 Btricted, prolonged, rostrate, and sub-capitate. Approaches P. di- 

 eepJiala. Cayenne. 



P. place?itula. — Small, very broadly lanceolate, oblong, ends con- 

 stricted, obtuse, rather produced, papillary ; near P. gastrum, but 

 larger. Vera Cruz, Mexico. 



p. porreda. — Striated, larger ; lanceolate, elongate dorsally, widely 

 expanded at the centre ; ends gradually attenuate, but broadly ol)tuse ; 

 pinnules oblique. Is near to P. decurrens. Central and North 

 America. 



P. praetexia. — Large, elliptic ; margins on the dorsal aspect ex- 

 panded, furnished with very broad pinnules, whilst the inter- 

 mediate space (median area) is gTanuliu- j striae seventeen in 

 l-1200th. Length 1 -288th. Fossil in Greek marl. 



P. Sillimanorum. — Striated ; large, lanceolate dorsally ; widely 

 expanded at middle or ventral surface, oblong; ends constricted, 

 produced, obtuse, and sub-capitate. Approaches Biomphalus Clame 

 Herculis. New York. 



P. sinuosa. — Small, narrow, linear lanceolate, sigmoid ; striae fifteen 

 in l-1200th. Mouth of the Elbe. Has the figure of Navicula 

 sigma, but is more slender. 



p. Tahellaria. — Bacillar, slender, of thi'ee segments (Trinodal) being 

 turgid at centre, and having capitate extremities. Is more slender 

 than P. nohilis, which it about equals in length. Central and North 

 America. (P. 15, f. 2L) 



