NEBELA SCOTICA. 61 
Since the above was written Playfair has described 
under the name of Nebela dentistoma var. lageniformis 
an Australian form which evidently belongs to this 
species, but is somewhat larger, being 126 w in length. 
6. Nebela vitreea var. sphagni Wailes. 
(Vol. II, Plate XXVIII, figs. 14-17.) 
Nebela vitrea 
PENARD (pars) Faune Rhiz. Léman (1902), pp. 372, 374, f. 6. 
CasH Brit. Freshw. Rhiz. IT (1909), pp. 121-122, pl. xxviii, ff. 14-17. 
Wares & Prenarp in Proc. R. Irish Acad. XXXI, txv (1911), pp. 18, 
50-51, 60, 61. 
Nebela vitrea var. sphagni 
WalItes in Jrn. Linn. Soc., Zool. XXXII (1912), pp. 125, 141. 
This variety is the Nebela vitrea described by Cash 
in Vol. IJ. It is a sphagnum-inhabiting species, much 
smaller than the large deep-water form described by 
Penard, which is 170» to 200 pw in length; in America 
this large form is found in sphagnum, attaining nearly 
300 p in length, but its testis somewhat different in 
structure from that of the Swiss type. 
N. vitrea var. sphagni usually measures from 80 p 
to 100 p» in length, but may vary between 66 mw and 
120 p, and is very similar in size to N. dentixtoma, 
with which species it is frequently associated in the 
British Isles. The test differs from that of the type 
by not being composed of regularly-arranged plates or 
scales the interstices between which are mostly 
covered by small overlapping plates; the aperture of 
the test also is bordered by proportionally smaller 
and more numerous grains of irregular shape, which 
in the type are usually only from seven to ten in 
number. : 
In Switzerland the large species is recorded only as 
occurring in deep water and var. sphagni from one or 
two localities, and even there it is rare; but in America 
the two are found in association amongst sphagnum 
and aquatic vegetation in shallow water. 
Both in America and Switzerland a medium-sized 
