26 PALUDINIDZ. 
B. TENTACULATA. B. LEacuit. 
Whorls much more con- 
vex. 
Suture much deeper. 
Umbilicus practically Umbilicus distinct. 
none. 
Mouth obliquely oval Mouth almost circular. 
and sharply angulated. 
Genus ITT.—HyYDRO6OBIA. 
1. H. siminis (similar to another species). 
Sub-conical, thin, semi-transparent, yellowish horn- 
colour; whorls five to six, rounded; sutwre deep; mouth and 
operculum oval; wmbilicus small. 
This species is only found between Greenwich and 
Woolwich, in ditches which are occasionally flooded 
by the tide. 
2. H. ventrosa (swollen). 
Conical, tapering, thin, glossy, semi-transparent; whorls 
six to seven, rounded; spire pointed; mouth oval. 
Abundant in brackish water in estuaries in England 
and Wales. | 
Var. I. minor. Much smaller, spire shorter. | 
Var. II. decollata. Truncate, eroded. 
