TAB. I. 



[In every case right-hand Scuta and Terga are figured ; hence the occludent margins are always to the left-hand.] 



Fig. 1. Scalpcllura magnum : — fig. (a) natural size, the rest magnified twice. 



(«) Imaginary restored figure, of natural size. (/() Rostral latus, inside view of, broad variety. 



(b) Carina, dorsal view. (?) Ditto, outside view of, narrow variety. 



(c) Scutum. (/c) Ditto, seen in profile, 



(d) Tergum. (/) Carinal latus, outside view. 



(e) Upper latus. (m) Ditto, inside view. 



(/) Carina, lateral view. (n) Ditto, outside view, broad variety. 



(ff) Rostral liitus, narrow variety. 



Fig. 2. Scalpellum angustiun -. — carina, dorsal and lateral views of, copied from Dixon's 

 ' Geology and Fossils of Sussex,' Tab. xxviii, fig. 9. 



Fig. 3. Scalpellum quadratum, fig. (a) natural size, the rest magnified twice. 



(a) Specimen as found embedded, with the («?) Carina, lateral view. 



valves in nearly their natural positions ; (e) Upper latus. 



the end of the rostral latus ought to (/) Rostral latus. 



touch the short basal side of the upper (ff) Carinal latus. 



latus. (k) Scutum, internal view. 



(b) Scutum. (i) Carina, dorsal view. 



(c) Tergum. (k) Ditto, section across middle of valve. 



Fig. 4. Scalpellum fossula; all the figures magnified twice, except (//), which is four 

 times the natural size. 



(a) Scutum. (e) Carinal latus. 



(b) Tergum. (/) Scutum, internal view. 



(c) Carina, side view. (ff) Carina, dorsal view. 



(d) Upper latus. (A) Ditto, section across middle. 



Fig. 5. Scalpellum trilineatum ; all the figures magnified twice, except (c and ^), which 

 are four times the natural size. 



(«) Carina, dorsal view. (d) Carina, section of, near apex. 



(6) Ditto, lateral view. (e) Tergum. 



(c) Ditto, section of, lower part. 



Fig. 6. Scalpellum semiporcatum ; scutum, magnified three times. 



Fig. 7. Scalpellum arcuatuni; all the figures magnified twice, except (y), which is four 

 times the natural size. 



(ff) Carina, dorsal_view. (e) Surface of carina, much magnified. 



[b) Ditto, lateral view. (/) Scvitum. 



(e) Tergum, inside view. (ff) Section across carina. 



(d) Ditto, outside view. 



Fig. 8. Scalpellum solidulum ; natural size, except (/). 



(a) Tergum. (d) Carina, section of upper part. 



(b) Carina, dorsal view. (e) Carinal latus, natural size. 



(c) Ditto, internal, almost lateral, view. (/) Ditto, much magnified. 



Fig. 9. Scalpellum simplex ; twice natural size. 



(ff) Carina, dorsal view. (b) Carina, lateral view. (c) Carina, section of. 



Fig. 10. Scalpellum tuberculatum ; largely magnified. 



(a) Tergum. (d) Scutum ; (e) basal margin, (/) occludent mar- 



(b) Carina, dorsal view. gin ; these two margins ought to form a 



(e) Ditto, lateral view. rather larger angle. 



Fig. 11. Scalpellimi (?) cretae; largely magnified. 



(a) Tergum. (b) Carina. ' (c) Scutum. 



