Bacillaria.] THE INFUSORIA. 211 



the middle slightly constricted, and extremities sub-acute. 

 (See group 155.) Eight transverse striae in l-100th of a 

 line. Found, living, at Gravesend, and fossil at Santa 

 Fiora. Length l-860th to 1- 100th. 



253. NAVICULA (?) splendida. The golden Navicula. 

 This beautiful and scarce species is striated, and has an 

 ovato-oblong lorica, as shewn in fy.150, 151, and 152; 

 the first is an oblique view the second a side view, and 

 the third a front (end) view of a dead specimen. Two 

 transverse striae in l-100th of a line. " In June, 1837," 

 observes Ehrenberg, " was the last time I saw this species. 

 The specimens resembled Turpin's Surirella striatella, 

 found in the sea at Havre, but were, nevertheless, dis- 

 tinguishable by their form and stripes. I saw them move 

 very often. The plates of the ova clusters are toothed, 

 and of a golden yellow colour." Length 1-2 10th to 

 l-100th. 



254. NAVICULA (?) bifrons. The two-beaked Navicula 

 is striated, resembles the preceding, but both ends of the 

 lateral surface are acute, and the ventral truncated. Three- 

 and-half striae in l-100th of a line. Found amongst oscil- 

 latoria, and fossil in the Isle of France. Length 1-2 10th 

 to l-100th. 



255. NAVICULA (?) striatula. The striated Navicula is 

 striated, and has an oval lorica, which is taper on its lateral 

 surface, and elliptical, or cuneiform, on its ventral one, as 

 seen in fig. 137 and 138. Thirteen striae in 1- 100th of a 

 line. This little creature was discovered by Dr. Suriray 

 in August, 1.826, and preserved alive for eighteen months. 

 The body is very transparent and colourless, and the 

 movement, which is slow, is only observed in those forms 



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