STUBBS : LAND AND FRESHWATER SHELLS OF TENBY. 361 



Planorbis fontanus. — In old pit-holes, full of water, near Hoyle's 

 mouth, common ; also sparingly in ditches on Gumfreston and Pen- 

 dine Marshes. 



P. nautileus. — Abundant where it occurs, though local. It has 

 been taken in quantity from a small pond by Penally Station, and from 

 sundry ditches on Gumfreston Marsh. The finest specimens come 

 from the pit-holes near Hoyle's Mouth, where it lives in company with 

 the last species. 



Var. crista. — Common, with the type. 



P. albus. — Common, and widely-distributed in the ditches on the 

 marshes ; it is also found in conjunction with the last two in the pit- 

 holes near Hoyle's Mouth ; the shells from the latter locality have 

 usually a wide expansion of the last whorl near the mouth. 



P. spirorbis. — Very abundant. It is found in almost every ditch 

 and pond in the neighbourhood. It grows to a very large size in a 

 ditch near the Black Rock, where specimens measuring 10 mm. in 

 breadth, or 4 mm. above the average size, have been taken. This 

 species is a favourite building material of the Caddis-larva, some of its 

 cases being built entirely of P. spirorbis ; even the living mollusc is 

 sometimes pressed into service. 



Var. albida. — Rare ; ditch by the Black Rock. 



Monstrosities. — A large number of remarkable distortions have 

 been taken in the Black Rock ditch (see above page 106). 



Bullinus hypnorum.— Abundant in several of the ditches on 

 the marshes. It is especially fine in the Black Rock ditch, where 

 specimens of 17 to 18 mm. have been taken. The shells from some 

 ditches are long and slender, from others short and stumpy ; the 

 colouring varies from pale yellow to deep reddish-brown, the darker 

 specimens, however, fading considerably in the cabinet. Planorbis 

 spirorbis is always found living with it in this neighbourhood, thus 

 confirming Mr. W. Nelson's note in this Journal, vol. 3, p. 115. 



Var. major. — Ditch by the Black Rock. 



Monst. decollatum. — Gumfreston Marsh ; not uncommon. 



For curious distortions from the Black Rock ditch, see above, 

 page 106. 



Physa fontinalis. — Not nearly so plentiful as the last species ; 

 it occurs locally on the Gumfreston and Penally Marshes. The shells 

 are, as a rule, rather small, and are usually encrusted on the upper 

 whorls with a confervoid growth. A specimen having an abnormally 

 inflated mouth was taken in the Black Rock ditch. 



Limnaea peregra. — Exceedingly abundant. As a rule only the 

 smaller forms are to be met with, but these show the customary 



