778 STRATIGRAPHICAL GEOLOGY. [Boox Vi. 
towards the close of Mesozoic time.’ Another genus, Pliosaurus, 
related to the last-named, was distinguishable from it by the short- 
ness of its neck and the proportionately large size of its head. 
Another extraordinary reptilian type was that of the pterosaurians 
or flying reptiles, which were hkewise peculiar to Mesozoic time. 
Those huge winged bat-like creatures had large heads, teeth in 
distinct sockets, eyes hike the Ichthyosaurus, one finger of each fore 
foot prolonged to a great length, for the purpose of supporting a 
membrane for flight, and bones, like those of birds, hollow and air- 
filled. The best known genus, Pterodactylus (Fig. 378), had a 
short tail and jaws furnished from end to end with long teeth. 
Others were Dimorphodon, distinguished especially by the length 

Via. 373.—Urrrr Oorrtic LAMELLIBRANCHS. 
a, Exogyra (Ostrea) virgula (D’Orb.); b, Ostrea deltoidea (Sby.) (4); ¢, Astarte Hart- 
wellensis (Sby.) (4); d, Cardium striatulum (Sby.) (3); e, Trigonia gibbosa (Sby.) 
4); f, Cardium dissimile (Sby.) (). 
of its tail, and Rhamphorhynchus (Fig. 379), also possessing a long 
tail, with a caudal membrane and having formidable jaws, which 
may have terminated in a horny beak. These strange harpy-like 
creatures were able to fly, to shuffle on land, or perch on rocks, 
perhaps even to dive in search of their prey. Lastly, the most 
colossal living beings of Mesozoic time, and, indeed, so far as we 
know, of any time, belonged to the extinct order of Deinosaurs, in 
1 On the distribution of the Plesiosaurs see a useful table by G. F. Whidborne 
Q. J. Geol. Soc. 1881, p. 480. 
2 See Marsh on wings of Pterodactyles, Amer. Jowrn. Sct. April 1882. The remark- 
able specimen of Rhamphorhynchus (It. phyllurus) from the Solenhofen Slate, described 
by this author, posscssed a long tail, the last sixteen short vertebrae of which supported 
A pe euliar caudal membrane which, kept in an upright position by flexible spines, must 
have been an efficient instrument for steering the flight of the creature. 
eaten Lily’ 
