GENUS CRYPTOGLENA. 419 



appear to be identical or closely allied to the Eutreptia viridis of Perty, previously 

 described. 



The author has quite recently, November 1880, received specimens of this inter- 

 esting animalcule, Distigma proteus, from Mr. Thomas Bolton, its companions in 

 the sample of pond water forwarded being Spirostomum feres, Paramcedum chrysalis, 

 Astasia trichophora, and Eugkna acus. The various protean forms reproduced from 

 Stein's work in the accompanying plate were abundantly exhibited during their 

 natatory condition by the examples examined, each change of contour being accom- 

 panied by the rapid flowing from one extremity to the other of the endoplasmic 

 corpuscles in the manner indicated in the foregoing diagnosis. 



Yet a week later the author has had remitted him, through the same agency, a 

 small phial absolutely teeming with the young eyeless condition of this animalcule, 

 as delineated at Figs. 49-5 1 of PI. XXI. These were found to be much more per- 

 sistent in shape than the adult zooids. While observed during the first four days to 

 change their form at more or less frequent intervals, it was noted towards the end of 

 the fifth and sixth days that they generally assumed a compressed spirally twisted 

 contour. The diagonal striation of the cuticle in two directions, as represented in 

 Stein's figure (PI. XXI. Fig. 49), was conspicuously developed in almost every 

 instance. The correspondence, in both size and contour, of the young Distigma 

 with Dujardin's Zygoselmis nebulosa is certainly very close, and suggests the proba- 

 bility of their proving to be synonymous. While going to press, the animalcules are 

 enjoying their active natatory existence, but owing probably to the absence of their 

 customary food, have scarcely increased in size, their average length, as when first 

 received, ranging from 1-800" to 1-500". 



GENUS IV. CRYPTOGLENA, Ehrenberg. 



Animalcules free-swimming, solitary, plastic and changeable in form, 

 enclosed within a rigid membranous sheath or lorica ; flagella two in 

 number, subequal ; endoplasm coloured green throughout ; an anteriorly 

 located eye-like pigment-speck usually developed. 



The representatives of this genus were considered by Dujardin to be so closely 

 related to Cryptomonas and the Phytozoon Chlamydococcus as to forfeit claim to 

 independent recognition, this verdict being coincided with by Pritchard. The author 

 of this treatise is, nevertheless, disposed to regard the type species, Cryptoglena 

 conica of Ehrenberg, as a well-marked independent form, most closely allied to the 

 genus Eutreptia, and occupying towards it a position corresponding to that which 

 subsists between the two genera Euglena and Trachelomonas. The Cryptoglena 

 lenticularis of Carter* is evidently a species of Chlamydococcus, while his C. cordata 

 has been transferred by Stein to the new genus Tetraselmis ; 



Cryptoglena conica, Ehr. PL. XXL FIG. 42. 



Lorica elongate-ovate or obconical, somewhat truncate anteriorly, more 

 or less pointed posteriorly, sometimes slightly curved ; body of animalcule 

 occupying the two anterior thirds of the cavity of the lorica ; flagella two 

 in number, evenly developed ; endoplasm bluish green; a conspicuous 

 scarlet eye-like pigment-spot developed at the anterior extremity; two 

 more opaque, ovate, and apparently amylaceous corpuscles frequently 

 present in the posterior region. Length, including lorica, i-iioo". 



HAB. River water. 



According to Ehrenberg the animalcules of this species progress forward rapidly 

 in the direction of their longitudinal axis, and if interrupted in their course, spring or 



* 'Annals of Natural History,' Oct. 1858. 



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