GENUS AST A SI A . 377 



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

 by Butschli 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 Anisonema, and as also observable in Paramecium 

 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 

 tnflata, 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 

 (Trachelius) 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 of Astasia trichophora. A slightly 

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

 appreciable distinctive characters is herewith appended. 



Astasia utriculus, 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 cucurbita, of 

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



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



