SCIEXCE-GOSSIP. 



345 



BRITISH INFUSORIA. 



Bv E. H. J. Schuster, F.Z.S. 



Part I. — Flagellata Eustcmata. 



(Continued from page 309.) 



T.N the last number some species of the genera 

 EugUna and Phacus were described. I will 

 now add descriptions of three further species of 

 these two genera before proceeding to others. 



EugUna spirogyra Ehrenberg. — The body of this 

 animal is elongate and sub-cylindrical, and when 

 fully extended is about seven or eight times as long 

 as broad and from 95 to 1S0 microns in length. 

 The anterior end is slightly truncate and bears a 

 slender flagellum of about the same length as the 

 animal itself. The posterior end is produced into 

 a transparent sword-like projection. The colour 

 varies in shade between bright green and brown. 



Fig. l.—Eui^Una %piros,yra (x 500). 



The nucleus is round and nucleolate and sub- 

 central in position. Anterior and posterior to it a 

 pair of large, round, amylaceous corpuscles may be 

 found, which Ehrenberg, in trying to prove the 

 high organization of the Infusors, considered to be 

 testes. The arrangement of the contractile vacuole 

 and its reservoir is as in E viridis. The cuticular 

 surface bears evenly-arranged oblique rows of 

 minute bead-like projections. The movement is 

 slow and steady. 



This animal was discovered by Ehrenberg in the 

 year of the accession of William IV.; it was found 

 again by bujardin in the Seine, on October nth, 

 in the year of Her Majesty's acct 



me across this species neai 

 frequently as the others described, because it 

 never occurs in vast shoals like EugUna viridis, 

 and is a clean-living animal, preferring running to 

 stagnant water, freshness to putrefati 



Pha; ■ animal occurs 



principally in stagnant water, ti. 

 pressed and leaf-like in shape, about one and a half 



d Ix.-ari a tail-HI I 

 jecnon about a quarter of its own length, v.!. 



directed obliquely upwards. The cuticular surface 

 is smooth, or sometimes presents a finely striated 

 appearance, especially when empty. The endo- 

 plasm is coloured bright green, and often contains 

 a large spheroidal amylaceous corpuscle. The 



Fig. 2.— Phacus pleuronectes ( x 300). 



nucleus is posteriorly located and spherical in 

 shape. The contractile vacuole is situated near 

 the anterior pigmented eyespot or stigma, and often 

 exhibits irregularly developed lateral branches. 

 Size, 20 to 50 microns. P. pleuronectes was described 

 by Miiller as Cercavia pleuronectes, and was trans- 

 ferred by Ehrenberg to the genus EugUna, and 

 afterwards by Nitzsch to the genus Phacus which 

 was established by him. 



Phacus pyrum Ehr. — This is subfusiform or 

 pear-shaped, about twice as long as broad. The 

 body is continued posteriorly in an acutely pointed 

 tail-like prolongation which is about equal to the 

 body in length. The cuticular surface is marked 

 with a series of oblique grooves, and owing to the 



Fig. 3.— Pluiais pyrum ( x 350). 



tenuity of the animal both sets of grooves are seen 



at the same time, so as to present an appearance 



of coarse network. It is about 20 to 30 microns 



in length. This animal occurs fairly commonly in 



pond water. It swims slowly, turning on its long 



axis. The species was discovered by Ehrenberg in 



1 1 ibed by him as EugUna pyrum. 



Ami' lis Ehr.— The k''""' ; Amblyophis 



i . very closely alii' '1 to EugUna, bul differs (rom it 



in having the posterior extremity rounded and nol 



produced Into the tail like expansion which forms 



such a well marked characteristii "I the genus 



1 . |m lian Perl and othen 



I thai the type spei Ics A virid ■ i 



n tailless variety ol Ek/ Una vlridi , bul 



Stein r>: e tablishi in thi ear i ; l.and 



