Naviculacea.'] infusoeial animalcules. 403 



medial lines inflated in the centre. Average length of A'alvc 

 l-300th. ; breadth at constriction 1 -850th. In brackish water near 

 Lewes. 



The front view of this species bears a close resemblance to tlie 

 Bame aspect in S. hiseriaia, (Smith) differing only in the appearance 

 of the costoe, which, in the present, assume the character of striae 

 rather than ribs. On the side view the constriction of the margins, 

 the inflation of the central fuiTOW, and line-like appearance of the 

 costce, afford sufficiently distinctive characters. The superficial 

 observer, regarding the side view only, might indeed confound this 

 species Avith immature specimens of Oymatopleura soha, but a slight 

 examination shows that the resemblance is one of outline merely. 



This seems an independent species, but it is unfortunate that its 

 discoverer has applied to it a name ah-eady in use to designate 

 another. 



SmuTRELLA splcndida. — Striated, on front \dew, ovate-oblong ; ends 

 rounded (fig.150, 151, and 152). Transverse stritc sti'ong, rib-like ; al» 

 large ; striae, two in l-1200th. "In June, 1837," observes Ehrcnberg, 

 "was the last time 1 saw this species. The specimens resembled 

 Turpin's SurireUa striatdla, found in the sea at Havre, but were, 

 nevertheless, distinguishable jDy their form and stripes. I saw them 

 move veiy often. The plates of the ova clusters are toothed, and of 

 a golden yeUow colour-. ' ' Length 1 -2 1 0th. to 1 - 1 00th. Found both 

 living and fossil. 



^. (}) bifrons. — Striated; resembles the preceding, but both ends 

 of the lateral sm-face are acute, and those of the venti-al, truncate. 

 Three-and-half striae in 1-1 200th. Common; living amongst Oscil' 

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

 1-1 00th. 



This species = S. liseriata (De Brebisson), the name adopted also 

 by the Rev. AV. Smith, who observes, in his note on this form, " In 

 living specimens I have noticed a circulation of the granular contents, 

 analogous to that which is seen in many of the Besmidiece, and in the 

 cells of the higher order of water-plants ; a further proof that it is 

 a single cell, and a presumptive evidence of its vegetable nature." 



S. folium. — Ovate, turgid and obtuse, slightly compressed, central 



