SCOTTISH ROTIFERS, COLLECTED BY THE LAKE SURVEY. 195 



not project so prominently outward in C. minuta, and the little lateral spines on the 

 anterior trunk segments. The skin was not stippled, but little importance can be given 

 to that character. 



In size it does, however, differ greatly, measuring only 77 ^ in length when feeding, 

 or little more than one-third that of C. pulchra, While size alone cannot be made a 

 primary specific character, in this case the difference between the related species is so 

 great that it gives greater weight to the other small differences. 



No Bdelloid which I have seen hatched is to such a degree smaller than the adult. 

 In common with many other Rotifers, the young, when hatched, is hardly inferior in 

 length to the parent, and very soon attains to all the adult proportions. The pellets 

 of food which filled both stomach and intestine showed that the last example of C. 

 minuta had been feeding for a considerable time. The pellets are relatively large, 

 measuring 6-7 m- 



The discs are inclined backward, and have central setse. The spurs measure 9 n 

 from tip to tip. 



The length of the antenna is equal to one- third of the diameter of the neck. 



Habitat. — Among Sphagnum, Blantyre Moor, 1902. In ground moss, Nerston, 

 near Glasgow, March 1905. 



On the first occasion of finding it, my acquaintance with Bdelloids was very 

 limited, and after a time I lost faith in the observation, and came to suppose that there 

 had been a mistake as to the power of the microscope used. The second occurrence of 

 the animal, years later, after a good deal of experience among Bdelloids, confirmed the 

 earlier record. 



Callidina circinata, sp. n. (Plate I. figs. 4 to 10). 



Specific characters. — Small. Head nearly square, with corona slightly exceeding the 

 collar, and very prominent dewlap overhanging first neck-segment. Upper lip of very 

 unusual form — sulcus between discs deep, bounded by two large processes connected 

 with the collar (the arrangement will be better understood from fig. 5 than from any 

 description). Antenna short, dorso-lateral processes large, widely spreading laterally. 

 Foot short, three-jointed. Spurs large, long, nearly parallel-sided, incurved, acute, inter- 

 space large, flat. Toes symbiotic (joined to form a perforate disc). Teeth, 3/3 or 

 2 + 1/1 + 2. Length vdien feeding, 213 m ; diameter of trunk, 71 m ; of corona 60 /* ; 

 tip to tip of spurs, 30 m. 



Habitat. — Among moss growing on dry wall at Nerston, East Kilbride, October 

 1906. Plentiful. 



This species affords another of those puzzles in distribution which are especially 

 familiar to students of the Rotifera. The moss on the wall was growing in little 

 detached cushions. One of these was casually pulled in passing, and was washed on 

 reaching home. When the strange species was found so abundant in it, the wall was 

 visited again, and surrounding tufts pulled, but none of the Rotifers found. 



, 



