GENUS ASTASIA. T^^y 



described later on. The contractile vesicle of Astasia tricJiophora has been shown 

 by Biitschli to exhibit a somewhat complex character, the water discharged in the 

 act of systole being partly driven into smaller lateral diverticula, as obtains in 

 Entosiphon and certain species of Anisone/iia, and as also observable in Fara/iiecium 

 and many higher Ciliata. Multiplication by fission in this species takes a longitudinal 

 direction. The presence of endogenously developed germs, as represented at 

 PI. XX. Fig. 1 8, has been recorded by Mr. Carter. 



Astasia contorta, Duj. 



Body colourless, semi-transparent, flexible and contractile, sub- 

 cylindrical, widest in the centre, bluntly pointed at the two extremities ; 

 the surface of the cuticle obliquely and closely striate, so as to impart to it 

 a twisted aspect. Length 1-425". Hab. — Salt water. 



A second marine species described by Dujardin under the name of Astasia 

 inflata, having the cuticular surface obliquely striate in a similar manner, and the same 

 approximate dimensions, but with a more ovoid body, is apparently a variation only 

 of A. contorta. 



Astasia flavicans, Ehr. 



Body extensile, conical or subcylindrical, rounded anteriorly, with a 

 short, blunt, tail-like posterior prolongation ; parenchyma enclosing yellowish 

 granules. Length of body 1-430". Hab. — Ditch-water. 



Astasia pusilla, Ehr. 



Body colourless, extensile, conical, largest and rounded posteriorly, and 

 with a short pointed posterior prolongation ; flagellum twice the length of 

 the body. Length of body 1-1440" to 1-400". Hab. — Ditch-water; social. 



This and the preceding are apparently variations only of the same form, and 

 are, as already remarked by Carter, closely allied to if not identical with the Astasia 

 {Tracheliics) trichophora of Ehrenberg and A. limpida of Dujardin. 



Astasia longifilis, Perty. 



Body persistent in form, hyaline, enclosing pale-green granules, the 

 anterior half exhibiting a longitudinal plait or furrow ; flagellum at least 

 three times the length of the body. Length i-iooo". 



Doubtful Species. 



A number of fresh-water species have recently been added to the genus Astasia 

 by De Fromentel,* but are in the majority of cases too ill-defined for re-identification. 

 The figures accompanying his descriptions might at the same time do duty in most 

 instances for one or other of the protean phases oi Astasia trichopJiora. A sliglitly 

 amended translation of Fromentel's diagnoses of such forms only as seem to possess 

 appreciable distinctive characters is herewith appended. 



Astasia utriciilus, From. — Body flask-shaped, inflated at the base and 

 rounded at the summit ; flagellum inserted somewhat on one side of the 

 neck-shaped anterior portion. Length 1-800". His Astasia cucnrbita, of 

 similar size and shape, is apparently identical with this form. 

 * ' Etudes sur les Microzoaires,' Paris, 1876. 



