Collembola and Thysanura of the Edinburgh District. 247 

 Isotoma palustris (Mull.). 



Isotoma palustris + 1, aquatilis, Lubbock's "Monograph." 



[Plate Vir. Figs. 18, 19.] 



This is another widespread and abundant insect, especially 

 among herbage in marshy places, and by the margins of pools 

 and ponds. The typical form — upper surface pale yellowish- 

 green, with one or three dark longitudinal stripes — is the 

 common one here ; but we have also the following varieties, 

 viz.: — var. prasina, Reut. (entirely yellow-green), and what 

 seems to be var. fucicola, Eeut. (uniform violet-brown). 

 Specimens agreeing with var. aquatilis (MlilL), as figured by 

 Schott (15), have also occasionally been found on pools 

 along with the type. A beautifully marked form (PL VII. 

 Fig. 18), with the palustris foot and mucro, which Dr Schaffer 

 tells us {in lit. 20/2/99) is his var. maculata, is common 

 in gardens and greenhouses. We can see practically no 

 difterence between it and the /. aquatilis of Lubbock's 

 "Monograph," except that in the latter the spots along 

 the back are more extensive, and form a distinct dorsal 

 stripe. Both have a few long abdominal hairs, the absence 

 of which is apparently considered by Schott to be a character 

 of I. palustris and its varieties. The difference in habitat 

 between this form and true palustris is also noteworthy. 



Eange exceedingly wide, and very similar to that of the 

 last-mentioned species — ISTovaya Zemlya and Siberia, to 

 Italy, Ireland, the Azores, California, La Plata (Parona), and 

 Bismarck Archipelago (Schaffer). 



Local data. — Pools on Bavelaw Moss, March, and Threipmuir Pond, 

 April 1896, abundant ; pond on top of the Braid Hills, and small marsh 

 lower down, common, July 1896, April and Sept. 1897, etc. ; Luffness 

 Marshes, Aug. 1896; Uphall, Sept.; Ravelrig, Oct.; Loch Ard, April; 

 Gartmorn Dam (Clackmannan), and reservoir near Cullalo (Fife), April 1897 ; 

 Isle of May, Aug.; quarry-hole near Longniddry, Sept., type and variety 

 aquntilis (MiiW.) ; Loch Leven, May 1898 ; Edgelaw Reservoir (Midlothian), 

 Oct.; Otterston Loch, March 1899. Y sec. fucicola: Bavelaw Bog, June 1897, 

 March 1899, etc., common. Var. prasina: Craigentinny Meadows, Jan. 1899, 

 a good many ; Bush, near Rosslyn, March, one ; Bavelaw Bog, May, a few. 

 Var. maculata: in gardens at Morningside and Aberlady, Sept. 1896, June 

 1898, etc., common on borders and gravel walks, and under flower-pots in 

 greenhouses ; banks of Dalhousie Burn, March 1898 ; etc. 



