Rhamphorhynchæ. Tail long and stiff. Hind-legs short. Pubis and ischium small, oblique to ilium, which extends less far anteriorly than in Pterodactylæ. Epipubic bones narrow and bent; they unite mesially and form a three-sided bow in front of the pelvis. Head with the middle holes and nares both small. Jaws never toothed to the anterior extremity.
Dimorphodontæ. Tail long and stiff. Hind-legs long. Pubis and ischium forming an expanded sheet of bone at right angles with the narrow ilium, which extends as far behind as in front [prepubic bones triangular (?) attached by the apex of the triangle]. Head with the nares and middle holes large. Quadrate bone large. Jaws with large teeth at the extremities, and small teeth behind. No sacrum.
Ornithocheiræ. Tail long and flexible. Hind-legs short. Pelvis as in Dimorphodontæ. [Epipubic bones with a small attachment, form unknown.] Head with the quadrate bone small. Sacrum of not fewer than three vertebræ.
In the Pterodactylæ the genera are—
Pterodactylus (Cuvier), in which the exterior nares are at the sides of the face, very large, and only partially, if at all, separated by bone from the small middle hole of the head. The head is elongated. The neck is long. Among others, it includes the species P. longirostris, P. Kochi, P. scolopaciceps, P. longicollum.
Ornithocephalus (Sömmerring), in which the anterior nares are entirely separated from the middle holes of the head, both being small, and the latter exceedingly small. The head is short The neck is short. The large ischium appears to be excluded from the acetabulum, and the ilium appears to extend less far forward than in Pterodactylus[AA].
[AA] So far as can be judged from figures, it appears to have but three bones in the wing-finger: what Cuvier regarded as a terminal and fourth joint, the bone n, Pl. XXIII. fig. 7, Oss. Foss., appearing to me to be the fibula of the tibia marked e. s in the same figure would be the terminal phalange, and r the first phalange, as may be proved by measuring them with those of the other hand, so that a phalange is missing from between them. Both the terminal phalanges appear to be hooked at the termination. Goldfuss figures the phalanges so as to make the bone which appears to be fibula in Sömmerring and Cuvier look like a fourth phalange.
Pachyrhamphus (Fitzinger). The nares are entirely separated from the middle holes of the head; both are large. The head is thick and massive. The prepubic bones meet mesially. No evidence of the number of phalanges in the wing-finger. The quadrate bone is massive, but has small attachment to the skull. Two sacral vertebræ. Wing-metacarpal very short. The type is P. crassirostris (Goldfuss).
Cycnorhamphus (Seeley). Nares very small, looking upward from a swan-like beak. The middle hole of the skull very large and elongated and lateral. Neck long. Wing-metacarpal long. Four joints in the wing-finger. Ilium widening in front. Epipubic bones meeting mesially. The type is Pterodactylus suevicus (Quenstedt).