124 C. F. ROUSSELET ON DIPLOIS TRIGONA. 



Furcularia longiseta, var. grandis (Tessin-Biitzow), PI. VII., 



Fig. 3. 



Furcularia longiseta of Ehrenberg, with its long unequal glassy 

 toes, twice to three times as long as the body, is a small Rotifer 

 often met with, crawling, or rather stalking, amongst the water 

 weeds. At our excursion to Hertford Heath, however, I came 

 across a startling variety of this pretty Rotifer. Not only was 

 the size of the animal fully twice as large, measuring -g^in. in total 

 length, of which the longer toe formed exactly one-half, but it was 

 adorned with two very large red spots in the lumbar regions, 

 exactly where the lateral antennas should be. The nature of these 

 spots is a mystery, as they can hardly be supposed to have a 

 visual function. A cervical eye situated on the under side of the 

 brain, a little distance from the tip, was present as usual. The 

 colour of the spots resides in two large vesicles, one on each side, 

 apparently attached to the integument ; these vesicles are clearly 

 seen in the mounted specimen, though the red colour has dis- 

 appeared, but I could not detect the lateral antennse. I observed 

 numerous examples ; in some the colour of the spots was a dark 

 crimson, in others a paler red, and in young forms the spots were 

 very minute but distinctly red. The integument is very soft and 

 flexible, and shows numerous close, longitudinal furrows when the 

 animal is extended, but these furrows disappear with the least 

 contraction. The toes are stout at the base, then tapering 

 gradually. Two or three very distinctly striated muscles enter 

 the hollow toes, traverse the wider part, and are attached to the 

 sides where the toe becomes narrower ; they do not traverse the 

 whole toe from end to end as depicted by Tessin-Butzotv. By 

 means of these muscles the animal is able to make sudden skips 

 forward or sideways out of the way of an enemy. The muscles 

 are of course also present in the smaller species, and were ob- 

 served by Ehrenberg, although he could not recognize the nature 

 of these bands. With the exception of the large red spots and the 

 size, this animal is exactly the same in structure as the smaller 

 species, and I have adopted as a principle not to make a new 

 species on account of size alone. I find, however, that Dr. G. 

 Tessin-Biitzow, in his pamphlet " Rotatorien der Umgegend von 

 Rostock," describes and figures F. longiseta as Monommata longi- 

 seta, and another very similar, but much larger species, ^in. long, 



