Ihsinidiea.'} infusorial akimalcules. 249 



ciilnv, with numerous conic tubercles. Length l-156th. Breadth 

 l-282ncl. Transverse view three times longer than broad, with 

 three rather distant inflations or lobes on each side, and one at each 

 end. 



Euastkitm: crassum. — Smooth; segments three-lobed, subquadri- 

 lateral ; terminal lobe cuneate, partly included in a notch formed by 

 the lateral lobes. Transverse view with tlu'ee lobes on each side, 

 and one at each end. Empty frond pimctate. 



Var. (5.) — Smaller, sides more concave; base more inflated ; and 

 the angles including the terminal lobe more elongated. Length 

 l-193rd to l-132nd. Breadth l-263rd. to l-260th. 



2. Segments sinuated ; terminal lobe exserted, and united with the basal 

 portion by a distinct nccJc. 



E. pinnatum. — Five lobed; end lobe exserted, dilated; upper 

 margin, of lobes horizontal. Basal lobes emarginate; the inter- 

 mediate ones smaller and entire. Empty frond punctate. Length 

 l-888th. Greatest breadth at basal lobes l-454th. 



E. humerosum. — Smooth, terminal lobes dilated ; emarginate; neck 

 partly included between the elongated middle lobes, which resemble 

 processes ; basal lobes emarginate. Empty frond minutely dotted. 

 Transverse view has three lobes on each side, and one at each end ; 

 whence it differs from E. affine. It is distinguished from all other 

 species in this section by its included neck. Length 1 -225th. Breadth 

 l-382rd. 



E. affine. — Three-lobed, with intermediate tubercles ; lobes emargi- 

 nate, end one dilated, its notch linear. Transverse view with four 

 lobes on each side. Empty frond punctate. 



E. ampullaceum is best recognized by its short segments, in which, 

 and its broad inflated base, it diftcrs from E. affine ; whilst the dis- 

 tinctly dilated terminal lobe separates it from E. didelta. Empty 

 frond punctate. Length 1-2 74th. 



E. insigne. — End view cruciform. Empty frond pimctate. The 

 transverse view differs from that of every other species in being con- 

 tracted at the middle. The inflated base and slender neck, conjoined 

 with its dilated end, are suflSciently characteristic. Length 1 -232nd. 



E. didelta. — Segments with inflated base, intermediate tubercles, 

 and notched, and scarcely dilated end ; transverse view, four shallow 

 lobes on each side, and one at each end. Segments pyramidal; 



B 



