314 J. E. S. MOORE. 



set spiralsj which extend down to the base of the shell. No 

 spirals are seen on the flat area. Aperture oval to subquad- 

 rate, columella moderately reflexed, so as to produce anteriorly 

 a wide and shallow groove towai'ds the point. Umbilical slits 

 scarcely indicated." 



Side by side with these old Jurassic shells I have had drawn 

 two corresponding views of Smith's Paramelania Damoni 

 from Tanganyika (fig. 1), the generic diagnosis of which runs 

 as follows : 



" Shell solid, ovate, conical, imperforate, longitudinally 

 ribbed, transversely lyrate, covered with a thin epidermis. 

 Aperture ovate, entire, indistinctly effuse at the base, last 

 whorl sometimes slightly prolonged inferiorly. Peristome 

 thick, margins joined by a callosity, operculum like that of 

 Typhobia."! 



The striking similarity of the two shells from these descrip- 

 tions will be at once apparent ; in fact, as Mr. Hudleston 

 remarked while we were examining the recent shells and fossil 

 side by side, " they are not only generically the same, but 

 specifically identical." 



The shells of the genus Paramelania were, however, 

 shown by the German authors I have quoted to be similar to 

 the Cretaceous genus Pyrgulifera, and, as objects which are 

 like the same thing are necessarily like each other, it becomes 

 a question for the systematists and the conchologists whether 

 or not the genus Pyrgulifera and Paramelania should be 

 quashed, and both replaced by the older genus Purpurina. 

 There are slight differences between the shells of the genera 

 Pyrgulifera, Purpurina, and Paramelania when they 

 are carefully examined side by side ; but these are not at all 

 sufficient to separate the specimens from one another as 

 specifically distinct, and, as Dr. Woodward pointed out to me, 

 those of the genus Paramelania approximate more closely to 

 the shells of the Jurassic genus Purpurina than they do to 

 the more recent Pyrgulifera type. 



In Hudleston's monograph there are represented two rather 

 > 'Proc. Zool. Soc.,' 1881, p. 559. 



