PLATE IV. 



Cor. lyra. 1 Fig. 1, young of variety with broad abdomen and closely arranged pilae. 

 Fig. 2, young of var. B, with narrower abdomen and rounded sides. Fig. 3, older stage of same 

 variety. Fig. 4, 5, nearly full-grown stage of same variety. Loc. Semur. Fig. 6, 7, full-grown 

 stage of variety with narrower abdomen, flattened sides, and closely arranged pilae, figure 

 reduced to about one half, loc. Filder. Fig. 8, young of same variety as Fig. 1, but transitional 

 to var. B. Fig. 9-11, young of var. C. Fig. 11 a, suture of same. Fig. 12-14, young of variety 

 like Fig. 1, 1 a, and Fig. 8, but with narrower abdomen and more flattened sides. Loc. Semur. 

 Fig. 15, 16, old specimen of var. C, with very convergent sides, and tubercles considerably 

 reduced, diameter 250 mm., loc. Gmiind. Fig. 17, sutures on the inner side (dorsum), 2 loc. 

 Semur. 



1 See Plate V. Fig. 1-3. 2 All the specimens figured were casts. 



