Fig. 10. Fig. 11.
The Trigonia carinata ( [Fig. 10] and [11]), one of a class of fossils which has particularly engaged the attention of Agassiz, is also found in the Cretacean series. It is figured in two different positions, that the elegant outline and the ornamental radiating striæ, regular tubercles, and denticulated margin may be fully seen.
In the Cardita we have the same heart-shaped form, but the ornamental surface is in many respects different. The regular curved lines proceeding from the hinge of the shell, which is itself most delicately formed, present in the Cardium mutonianum ([Fig. 12]), the tuberculata of Sowerby, a most pleasing arrangement of striations. The regularity of these, as shown in the woodcut, particularly recommends this specimen and others of its class as admirably adapted for ornamental purposes, where very delicate and elaborate workmanship can be admitted.
Fig. 12.
The Opis Sabandiana ([Fig. 13]) is another of these elegant shells more remarkable for the regular form of its outline than for any elaboration of the striæ which traverse it, in this respect standing in pleasing contrast with the preceding figure.
Fig. 13.