228 F. W. EDWARDS. 



Mr. M. E. Mosely has presented to the British Museum a number of pupae and a few 

 larvae ; masses of the former were in a jar in Mr. Mosely's possession collected by 

 the late F.M. Half ord and labelled " Crickmere, 16.ix.l894;" Mr. Mosely also 

 collected a few pupae himself in the River Test, Hants. 



The species must be very similar to the North American S. piscicidium, but that 

 is described as having yellow legs. 



3. S. variegatum, Mg. (figs. 16, 4^). 



Larva. — General colour brownish or dark grey, without special markings on the 

 body. Head usually dark at the sides above and below the eyes ; clypeal markings 

 often faint, when present usually ill-defined, but arranged much as in S. ornatum. 

 Antennae 5- jointed, the first as long as the next two or three together ; second some- 

 times indistinctly divided in the middle, twice as long as the third ; third shorter 

 than the fourth. Mentum with 9 teeth in the terminal row, all slightly trilobed, 

 the small lateral lobes pale ; middle tooth very large ; about 8 long hairs on each side 

 almost in a straight line. Thoracic proleg with a pair of rather strongly chitinised 

 plates above the ring of teeth. Last abdominal segment without ventral papillae. 

 Anal sucker with about 85 rows, each with 12-15 hooks. Anal gills each with 8-10 

 rather long branches. Skin round anus with numerous minute dark scales, composed 

 of short rows of spines (5-8 in each) ; the scales are much smaller and less numerous 

 than those of S. ornatum. 



Pupa. — ^Respiratory filaments about as long as the pupa, six in number, in three 

 very shortly stalked pairs ; all the filaments more or less in the sam.e plane ; upper 

 pair rather thicker than the others. Cocoon very large, fully a third longer than the 

 pupa, in texture close- woven behind and above, but with an open network on the 

 sides towards the front ; this network often, but not invariably, continued round 

 the front of the cocoon and enclosing the ends of the respiratory tubes^ the cocoon 

 then approaching the " boot "-shape of S. equinum. 



Habitat. — Swift stony rivers and streams, both larvae and pupae on the upper 

 surfaces of stones where the current is strong but smooth and the water not too deep. 



Material collected. — ^Larvae and pupae were found in great abundance in early 

 June 1920 in South Devon : in the River Dart through Holne Chase, the River 

 Teign between Fingle Bridge and Christow, and the river Yeo near Ashburton, 

 associated with S. tuberosum and S. reptans but in much larger numbers. A female 

 specimen hatched from a pupa collected in 1912 at Ewbank Scar, Kirkby Stephen, 

 Westmoreland (C. B. Williams), in company with larvae and pupae of >S. monticola, 

 Fried. 



Blood-sucking. — In August 1916 Mr. C, L. Walton sent me females from Crosswood, 

 Cardiganshire, which were taken in company with S. ornatum " attacking horses 

 about nose and eyes and on belly." 



Variation. — There seems to be great variation in the colour of the larval head, 

 some being much darker than others. 



Reference. — Friederichs has described the larva, pupa and adult of this species 

 as S. venefica, sp. n. 



