Fig. 131.—Aëtobatis subarcuatus, from Bracklesham.
Rhinoptera.—The cephalic appendages are bent inwards, and situated at the lower side of the snout. Nasal valves confluent into a broad flap, with free margin. Teeth broad, flat, tessellated, in five or more series, the middle being the broadest, and the others decreasing in width outwards. Tail very slender, with a dorsal fin before the serrated spine.
Fig. 132.—Rhinoptera woodwardi; fossil.
Fig. 133.—Rhinoptera polyodon.
Seven species from tropical and sub-tropical seas are known; of Rhinoptera polyodon nothing is known except the jaws; and as its dentition is very peculiar, no opportunity should be lost of obtaining and preserving entire animals. Teeth very similar to those of existing species, and described as Zygobatis, occur in the Norwich Crag and in Miocene formations of Switzerland.
Dicerobatis (Cephaloptera).—Cephalic appendages pointing straight forwards or inwards. Nostrils widely separated from each other. Mouth inferior, wide. Both jaws with very numerous and very small flat or tubercular teeth. Tail very slender, with a dorsal fin between the ventrals, and with or without a serrated spine.
Ceratoptera.—Cephalic appendages pointing forwards or inwards. Mouth anterior; wide. Teeth in the lower jaw only, very small. Tail very slender, with a dorsal fin between the ventrals and without spine.