554 



SYSTEMATIC HISTORY OF THE INFUSORIA. 



D. Dryas. — Ovate ; aperture entire, 

 truncate ; surface marked wdtli longitu- 

 dinal lines of ovate cells, which decrease 

 in size posteriorly. 1-1170". On roots 

 of trees. 



D. oligodon. — Smooth, oblong, sub- 

 cylindrical; aperture with eight strong 

 denticulations. 1-1000". This spacies 

 and the two following found in Kur- 

 distan. 



D. reticulata. — Ovate, surface marked 

 by a net- work of minute cells ; aperture 

 simple, large. In its interior are nu- 

 merous particles like aggregated buds; 

 the margin of the foramen is sometimes 

 dentate. 1-880". 



D. squamata. — Ovate, with large loose 

 areolae, looking like scales (squamse) ; 

 aperture denticulate, truncate, contracted. 

 1-1450". 



D. spirt ff era. — Pyriform, smooth ; neck 

 distinct, cylindrical, truncate; orifice 

 large, entire ; opposite end turgid ; round- 

 ed. The surface presents four spiral lon- 

 gitudinal lines. 1-36"'. Bavarian Alps, 



The first of the appended species is 

 from Dujardin, the others from Schlum- 

 berger (Ami. des Sciences Nat. 1845, 

 p. 254) :— 



D, glohidosa (xxi. 10). — Brown, glo- 

 bular, or ovoid, smooth. 1-260" to 

 1-105". Near Paris. 



D. depressa. — Diaphanous, ovoid, de- 

 pressed, resistant ; its surface divided by 



slight fissiu'es (lines) into numerous 

 small and irregular polygonal sections. 

 1-220". Aperture with an uneven mar- 

 gin. In springs in the Vosges. 



D. gifjcvntea. — Greyish brown, rough, 

 as if strewed with particles of sand, 

 ovoid, elongated, and contracted an- 

 teriorly. 1-325" to 3-325". It ap- 

 proaches D. proteiformis, but differs in 

 its more elongated form, in being con- 

 tracted anteriorly and almost pyriform, 

 sometimes depressed, and lastly in its 

 greater size : margin of aperture uneven. 



D. tricuspis (Carter). — Processes occu- 

 pied by granules, greenish ; testa ovoid, 

 little incrusted ; its foramen tricuspid in 

 form, or of trefoil shape {A. N. H. 1856, 

 xviii. p. 247). Fresenius appears to have 

 met with this form, but considers it only 

 a variety of D. ohlonga. 1-320". 



D. ? marina (Bailey), — Shell silici- 

 ous (?), ovoid or lagenoid, with a con- 

 tracted neck and circular aperture ; sur- 

 face divided by oblique lines into quadri- 

 lateral spaces. oV of 1-1000", diam. 1^ of 

 1-1000". 



A single specimen was found in sound- 

 ings taken from a depth of 2750 fathoms, 

 which had been cleaned with acids. 

 This resistance to acids induced Dr. 

 Bailey to consider the shell silicious, 

 but we now know that chitinous shells 

 are equally unaffected. The discoverer 

 doubted its being a Diffiugia, on account 

 of its marine habitat. 



Genus SPIRILLUSTA. — Lorica tubular, silicious (?), rolled in a spiral 

 manner, like a Planorhis. It is allied to Difflugia by its silicious lorica (for 

 acids have no action on the shell). This genus probably agrees with the 

 Spirulina of Bory de St. Vincent; but the latter name has been otherwise used 

 by Ehrenberg to designate a genus of Polythalamia. 



Spirillina vivipara (xi. 37). — Shell 



})orous, convoluted as a circular, spiral, 

 lorizontal tube, hyaline and smooth. 

 Yovmg loricpe may often be found con- 

 nected with it. In the sea — Vera Cruz, 

 Mexico. 



The form of this species recalls that 

 of many undoubted Polythalamia, whilst 

 it has no fellow amongst the Infusoria. 

 Ehrenberg has likewise represented ap- 



parent dots or pores on its surface, like 

 those through w^liich the filifonn pro- 

 cesses of Polythalamia are protruded; 

 and the only reason implied in Eliren- 

 berg's account for reckoning it among the 

 Polygastrica is its silicious shell : it is, 

 however, most probably chitinous. It 

 will be noted that Ehrenberg is inclined 

 to believe it viviparous. 



Genus ARCELLA (XXI. 7-9, 15). — Variable processes, numerous and 

 hyaline; single processes cleft into many, and expanded in a radiating 

 manner ; lorica flattened, shield-like. The lorica varies much in structure in 

 the different species. Eor instance, in A. vidyaris it exhibits regular and 

 delicate facets ; in A. dentata the facets are large and crystalline ; in A. acu- 

 leata it is beset with spicula; and in A. Jiyalina it is homogeneous and 

 clear. Vacuoles are seen filled with coloured vegetable substances ; and in 



