382 



met with in al! parts of the country in slow 

 streams, ditches and canals. 



Leachii- — This is a smaller shell than the 

 last, of similar shape and color, the whorls are 

 rather more rounded, and the aperture is 

 more nearly round The operculum is spiral, 

 with the nucleus in the centre. It also dwells 

 in slow streams, canals, ditches, &c, throughout 

 the country. 



Genus, Paludina 



This genus contains two species of 

 comparatively large size, being the largest 

 among the Land and Fresh-water operculated 

 molluscs, the shells are conical with rounded 

 whorls ; the operculum is formed of 

 concentric rings. The animal has a protruding 

 snout, the tentacles are rather stout, and 

 united to them, at the base and at their outer 

 sides are the eye stalks, there is a lobe at each 

 side of the head behind the tentacles, 

 that at the right hand side forming the 

 opening to the breathing organs. The 

 Paludina are distinguished by their mode of 

 reproduction ; while other molluscs deposit 

 eggs from which the young in due time emerge, 

 these retain the eggs in the ovary, where they 

 are hatched, and the young do not leave the 

 parent for some time after, when they at 

 length come forth alive, three or four only 

 being ejected each day. There are two 

 specie^ Contecta and Vivipara. 



Contecta.-~This isjthe larger of the two 

 species, the shell measuring about an inch 

 across at the widest part when fully grown, it 

 is somewhat top shaped, with conical spire, 

 the whorls much rounded and with an umbili- 

 cus, it is encircled with three dark bands of a 

 purplish color, the ground color being olive- 

 green. The animal is c-i a brownish color 

 speckled with yellow. it is found in the 

 Southern and Midland p< rtions of England, 

 in ponds, slow streams, canals, &c. 



Vivipara- -A very similar shell to the 

 last, but a little smaller, the whorls not so 

 much rounde 1, the umbilicus much smaller, 

 and the apex a little more blunt ; it is similarly 

 rncird^d with three dark reddish bands. 



It may be met with in similar situations to 

 the last, and in the same parts of the country. 

 (To be continued.) 



BRITISH FERNS. 



By Id. And lews, Aldborough. 

 Genus 7, ,colopendrium. 



Dorsal-fruited ferns, having elongate sori in 

 parallel pairs, the indusia bursting along the 

 centre of the sori. Comprises Vulgave only. 



Scolopendrh m Vulgare (Hart-s- 

 Tongue Fern). — Grows in tufts from 6 to 12 

 inches high. Fronds are strap-shaped, and 

 much elongated, acute attheapex and cordate 

 at the base. The margin is entire, with shaggy 

 stipes about a third of their entire length. 

 The fronds have i strong midrib or costa, 

 with forked veins and parallel venules, sori 

 are oblong, and lie in the direction of the 

 veins. Fronds ap >ear in Maw Found on 

 hedge-banks, old walls, ruins, and in wells. 

 It is very common. There are 39 varieties. 

 Geniu 8, Ceterach. 



1 >orsal-fruited ferns, with obsolete indusia, 

 and sori hidden am mg the scales. Comprises 

 Ojficinariim only. 



Ceterach Officinarum is a dwarf, 

 ever-green, and h indsome fern, growing in 

 tufts. The frond-, are from 2 to 6 inches high. 

 They arepinnatifid, the upper surface is an 

 opaque green, and the under surface densely 

 covered with rust-i olored scales. The pinnae 

 are ovate, with lobed margin. Venation is 

 indistinct. Sori -ire irregular, and partly 

 concealed by the e laffy scales, but ultimately 

 protrude between them. Found on walls, 

 1 bid buildings, arid ruins. Occurs pretty 

 I plentifully; 



Sub-Grc ip 4, Blechnea. 



Ferns whose s ri have indusia, forming 

 longitudinal lines between the midrib and 

 margins of the lea'icts. 



Genus >>, Bleohnum. 



Dorsal-fruited 1 ,-rns, having the sporangia 

 in a continuous li :e between the midrib and 

 margins of the segments, covered by linea 



