Vol. 70.] DEVELOPMENT OF TRAGOPHYLLOCERAS LOSCOMBI. 301 



EXPLANATION OF PLATES XLVIII-L. 

 Plate XL VIII. 



Tragophylloceras loscombi (J. Sowerby), from 10 feet above the Belemnite- 

 Stone on Black Ven, Charmouth. 



[The numbers in parentheses refer to the collection of Mr. W. D. Lang. All 

 the figures are enlarged, and represent internal casts in iron-pyrites.] 



Figs. 1 a & lb. Protoconch from above and from below (1957 a). X 70. 



2a & 2b. Protoconch from above and from below (2019). x 70. 

 Fig. 2 c. Frontal aspect do. X 70. 



Figs. 3 a & 3 b. Lateral aspect and view from below (1999). X 70. 



4 a & 4 b. The same specimen at the second suture. X60. 

 Fig. 5. Specimen (1962 a) showing first and second sutures. X70. 



6. The same specimen at the seventh suture. X55. 



Plate XLIX. 

 Tragophylloceras loscombi (J. Sowerby). 



(All the figures are enlarged, except fig. 1. which is of the natural size. 

 Figs. 2-4 represent internal casts in iron-pj-rites.) 



Fig. 1. Front-view (outline) of Sowerby's type (B. M. No. 33425). ' Blue 

 Lias ' of Lyme Regis. 

 2 a. Young shell at the diameter of 1*2 mm, showing constrictions (1957a). 

 From 10 feet above the Belemnite- Stone on Black Yen. X35. 



2 b. Section of the same. 



3 a. Shell at the diameter of 2*8 mm. (1206). From a rainwashed slope at 



the horizon, of the Upper Limestone, 35 feet above the Belemnite- 



Stone on Stonebarrow Cliff. Xl8. 

 3 b. Suture at the diameter of 1*8 mm. 

 3 c. Suture at the diameter of 3 mm. 

 3d. Internal (dorsal) suture at the diameter of l - 8 mm.. 

 Figs. 4a-4c. The same specimen (1206) at a diameter of 6*25 mm. ; a & b = side- 



and sectional views, X4|; c = side-view, Xl5. 



Plate L. 



Figs, la & lb. Rhacophyllites stella (Sow.). Lower Lias of Spezia (Brit. Mus. 

 C 15569). Diameter =6 mm. x4. 



2 a & 2 b, The same at the diameter of 4 mm. X 8. 



3 a-3 c. Sutures of the same specimen : — 3 a at the diameter of 4 mm. ; 



3 b at 6 mm. ; 3 c in the adult. 

 Fig. 4. Psiloceras aff. erugatum (Bean-Phillips). Planorbis Zone of 



Robin Hood's Bay. Suture-development, enlarged. The 

 numerals indicate the diameters in mm. 

 5. The same. Asymmetrical suture of another specimen. S = 



position of siphuncle; M= median line. 

 Radial line of Tragophylloceras loscombi (J. Sowerby) type, 

 do. do. (in Wright). 



Figs. 8a & 8b. Do. do. Tragophylloceras ambiguum (Simpson) in 



Buckman. 

 Fig. 9. Do. do. Psiloceras plaiiorbis (Sowerby) in Quenstedt. 



Euphyllites struckmanni (Neum.) in Wahner. 

 RhacopliyUites nermoesense (Herb.) in Wahner. 

 Mojsvarites planorboides (Giimb.) in Pom- 



peckj. 

 Monophyllites agenor Mojs. (in Poinpeckj). 

 Monophyllites simonyi (Hauer) in Pompeckj. 



6. 



7. 

 .8a & 8b. 



Radial line 

 Do. do. 

 Do. do. 



9. 

 10. 

 11. 

 12. 



Do. do. 

 Do. do, 

 Do. do, 

 Do. do. 



13. 

 14. 



Do. do. 

 Do. do. 



