PLATE VII. 



Cor. trigonatum. Fig. 1, old specimen of the stout variety, showing adult suture and the 

 closer approximation and degenerative changes in lobes and saddles in old age, figure reduced to 

 about one third. Loc. Aalen. 1 



Cor. bisulcatum. Fig. 2-4, young. Fig. 5, 6, young with earlier developed and more 

 prominent pilae. The coarse heavy pilse of the last figure are remarkable, and the young has 

 also a broader abdomen and a form like an older stage of Cor. latum. Fig. 7 shows the decrease 

 in breadth of the abdomen with age, which is also seen in Fig. 6. Fig. 8, older stage, with 

 suture. Fig. 9, 10, nearly full-grown stage of same variety. Loc. Semur. 



Agas. Scipionianum. 2 Fig. 11, 12, young of gibbous variety. Fig. 13, 14, young, show- 

 ing development of pilae from folds. Fig. 13 a, 14 a, enlarged sutures also indicated upon 

 corresponding figures. Fig. 15, front view of same specimen as that of Plate X. Fig. 13. 

 Loc. Semur. 



1 See, for ventral view of same, Plate VI. Fig 3. 

 - See Plate X Fig. 11-13. Summ. PI. XIII Fig. 7. 



