PLATE IX. 



Sowerbyi-zone (Concavum-beds). 

 Figs. 1 — 7. — Lioceras concavum, var. v-scriptum, 8. Buchman. 



Fig. 1. — A fine adult form, snowing small hollow umbilicus, and complete 

 mouth-border. The test is well preserved. Bradford Abbas, Dorset. Collected 

 by my father. 



Fig. 2. — Front view of the same specimen. 



Fig. 3. — View of the other side of the same specimen, where the test is absent, 

 showing the ridges and furrows produced by the varying thickness of the test. 

 This view of the same specimen was figured by my father in the ' Quart. Journal 

 of the Geological Society,' 1881. 



Fig. 4. — Suture-lines of the specimen in situ, showing part of siphonal, and 

 superior and inferior lateral lobes, and siphonal and superior lateral saddles with 

 the accessory lobes in them, and also the manner in which the previous lobes 

 are penetrated by those succeeding. The cross shows the position of the last 

 suture-line, indicating a body-chamber of exactly half a whorl. 



Fig. 5. — A front view of a young specimen. The carina is, if anything, rather 

 too distinct. 



Fig. 6. — Side view of the same specimen with nearly all the test preserved. 

 This is a young immature form, with a somewhat smaller umbilicus, and is in 

 reality the young of the specimen figured in Plate VI. (The carina seems a little 

 too prominent.) Bradford Abbas, Dorset. Collected by my father. 



Fig. 7. — Side view of a small shell, showing the small pointed lateral process, 

 also the less inclusion of the whorls in youth. The greater portion of the test is 

 preserved. Bradford Abbas, Dorset. My Collection. 



Figs. 8 — 10. — Lioceras concavum (Sowerby) ; abnormal form. 



Fig. 8. — Side view showing regular whorls and umbilicus. Bradford Abbas, 

 Dorset. Collected by my father. 



Fig. 9. — View of the other side of the same specimen, showing abnormally 

 formed whorls and umbilicus, and with indentations on the inner area of whorl. 



Fig. 10. — Front view of the same specimen, showing one side with regular 

 concave inner margin, the other shorter and without any. The test is entirely 

 preserved in this specimen. 



