The Scottish A T aturalist. 263 



intervening cell ; oospores obovate or subglobose ; antheridia 

 cylindrical, erect, scattered on distinct threads, with an apical, and 

 two or more lateral openings (see Fig. 6 a). The plant grows 

 generally in ditches overflowed at high tide by sea water. 



Vaucheria litorea, Hofm. (Fig. 8). Dr. Nordstedt met 

 with this species at Inverness, at Greenod, near Ulverstone, and 

 in Caermarthen. 



It differs as follows from Vaucheria piloboloides, Thur. The 

 latter species, as seen growing at Weymouth, forms small loose 

 patches a few inches in extent, on the edge of sandy ledges, in 

 pools near low water mark, each thread standing up distinctly like 

 so many pins in a pin-cushion, the stems, however, are matted 

 below, so that it is very difficult to wash clean, so as to preserve 

 its habit of growth. The antheridia I have not observed, although 

 the asexual reproductive organs, or propagula, appear to be not 

 uncommon (see Fig. 8). The oogonia are distinct from those of 

 V. sphcerospora by being lens-shaped, instead of globular. The 

 antheridia are described as terminating short branches, cylindrical, 

 with an apical, and several lateral, shortly conical apertures. 



The marine species which may yet be discovered in Britain are 

 as follows : — 



V. intermedia, Nordst. 



This much resembles V. sphcerospora, but has nearly sessile 

 oogonia, with obtuse, cylindrical antheridia, either immediately 

 beneath, or attached to, the oogonium itself (see Fig. 5). 



V. coronata, Nordst. (Fig. 4). 



This species is easily recognised by the circlet of short prominent 

 apertures that exist on the apex of the oogonium, which is nearly 

 sessile, the oospore occupying the centre of the cavity, but not 

 filling it ; the antheridia are sometimes close to the oogonium, and 

 sometimes at a distance from it, but on the same thread ; they are 

 cylindrical, with one, or sometimes two, lateral openings (see Fig. 4). 

 V. coronata has a csespitose habit like V. sphcerospora, but it grows 

 in wetter places, and is often intermixed with V. intermedia. It 

 is less compact than V. synandra. 



The majority of the maritime species of the genus form dense 

 spreading green turfs, extending for several feet over the muddy 

 sloping sides of estuaries or creeks, into which a small fresh-water 

 stream enters. Some form patches among grass and thrift in 

 mudflats, and a few are found at lowest tide mark (V. dichotoma, 



