PLATE V. 



Cor. lyra. 1 Fig. 1-3, half-grown shell of same variety as Fig. 6, 7, Plate IV., showing how 

 narrow the abdomen is in some specimens before the shell was full grown. Fig. 3 a, suture, 

 slightly older than that delineated on Fig. 2, showing the changes which had taken place. Loc. 

 Semur. 



Cor. G-muendense. 2 Fig. 4, half-grown specimen, exhibiting variety with discoidal form 

 and compressed whorls, figure reduced to less than one half. Fig. 5, full-grown specimen of 

 same .variety with marks of approaching old age upon the last whorl, figure reduced to less than 

 one half. Loc. Semur. Fig. 6, specimen in which the wider abdomen and young proportion of 

 Fig. 4 were maintained until a much later stage than in Fig. 4 or 5, figure reduced to about one 

 half. Fig. 7, umbilicus of Fig. 6, about natural size, to show the smoothness of the young 

 whorls. Loc. Aargau. Fig. 8, 9, same variety as Fig. 5, but showing the effects of senile 

 decline in the convergence of the sides, degeneration of the pilse and tubercles, diameter 

 205 mm., loc. Semur. 



1 See Plate IV. 2 See Plate VI. 



