10 THE ROTIFERA. 



This Callidina was discovered by Dr. Carl Zclinka, inhabiting the JungermanJim 

 Fridlania dilatata, F. iamarisci, and Badula complanata. Dr. Zelinka has jJubhshed 

 an elaborate treatise on this form, exjolainiug its structure most minutely, and accom- 

 panied by many large drawings and diagrams. The main differences, between it and 

 the other species of the genus, are in the mastax and the foot. The first has rami with 

 unequal numbers of teeth ; and the second has toes, each of which ends in five small 

 tubes, leading up to the foot-glands. Dr. Zelinka kindly sent me his treatise, and I at 

 once went to some elms, on Clifton Down, on whose trunks I knew that the above-named 

 plants were to be found. There was a bitter frost, and the snow lay deep ; and though 

 I procured plenty of the brown withered-looking Fridlania, I had little hope of finding 

 any Eotifera in its cups. However, on tearing out the brown mass with needles, I saw 

 some green stems under the brown ones; and on moistening these under the microscope, 

 I soon had the pleasure of seeing first one Callidina, and then another, come to life, 

 stretch its head out of the cup in which it had been curled up, and unfurl its wheels 

 (fig. 12 a). Dr. Zelinka describes the foot-glands (fig. 12 6) as consisting of four rows 

 of cells, and their long excretory ducts as discharging through ten little tubes, five of 

 which project from each toe. A somewhat similar arrangement has been discovered 

 by Dr. Zelinka in Discopus Synaptm, and I know of no other example among the 

 Philodinadce ; but a mastax in which the rami have an unequal number of teeth is 

 occasionally met with ; individuals, of the same species, differing from each other in 

 this respect. It is obvious how the Callidina contrives to exist in its strange home. 

 Eain usually takes a definite course down the furrows in the bark of a tree, just as it 

 does do\\-n the valleys of a river-basin ; and the Jungermannia follow its track. The 

 green cups are filled by the rain, and protected from rapid evaporation of their contents 

 by the minuteness of their apertures, and their position on the under side of the frond. 

 They thus form suitable homes for the Callidina ; which, when at last the water begins 

 to dry up, draws in its head and foot, shapes itself into a ball, exudes a gelatinous 

 covering around itself, and waits for happier times. 



Length, (fully extended) cir. ^'^inch. Habitat. Cups and leaves of Jungcrmannice. 



Callidina Leitgebii, Zclinka (205). 



SP. CH. Body of sixteen segments, longittodinally ftirrowed, colourless, alimcntartj 

 canal generally ftdl of green alga ; teeth in one ramus five, in the other six ; CESophagus 

 tuith a loop ; corona large, with a short pcdimcle ; upper lip not notched, hut loitli a rnedian 

 projection; spurs sVtori ; tzvo toes, each ending in five minute holloxo prominences. 



A very similar animal to the last; and also found by Dr. Zelinka in Jungermannios. 

 It is said to have the same peculiar toes. 



Length, cir. -i J„ inch. Habitat. Cups and leaves of JungermannicB (Zelinka). 



Callidina quadeicoenifeea, Milne. 



Macrotrachcla quadricornifera Milne (18G). 



SP. CH. "Bodj stoid, and Philodinc-like ; corona large, not constricted ; proboscis 

 very thick and square ; foot ahout \ of total length, and with three short thick iocs ; 

 spurs /o!<r, thei-e being an extra pair on the top joint of the foot. 



This species of Mr. Milne's is remarkable for the extra pair of spurs on the foot. 

 The general shape is not unlike that of P. citrina, and the wheels are very similar ; but 

 the foot is much shorter in proportion. The mastax is largo, and so is the contractile 

 vesicle. There is a short, broad, perforate antenna, armed with fine setse ; and the 

 transverse muscular system is well developed. 



Length, jL inch. Habitat. Neighbourhood of Glasgow (Milne). 



