on the land; but in some cases, at any rate, the hind-limbs were much longer and stronger than the fore-limbs; and there seems to be no reason to doubt that many of these forms possessed the power of walking, temporarily or permanently, on their hind-legs, thus presenting a singular resemblance to Birds.  Some very curious and striking points connected with the structure of the skeleton have also been shown to connect these strange Reptiles with the true Birds; and such high authorities as Professors Huxley and Cope are of opinion that the Deinosaurs are distinctly related to this class, being in some respects intermediate between the proper Reptiles and the great wingless Birds, like the Ostrich and Cassowary.  On the other hand, Professor Owen has shown that the Deinosaurs possess some weighty points of relationship with the so-called “Pachydermatous” Quadrupeds, such as the Rhinoceros and Hippopotamus.  The most important Jurassic genera of Deinosauria are Megalosaurus and Cetiosaurus, both of which extend their range into the Cretaceous period, in which flourished, as we shall see, some other well-known members of this order.

[Illustration:  Fig. 180.—­Skull of Megalosaurus, on a scale one-tenth of nature.  Restored. (After Professor Phillips.)]

Megalosaurus attained gigantic dimensions, its thigh and shank bones measuring each about three feet in length, and its total length, including the tail, being estimated at from forty to fifty feet.  As the head of the thigh-bone is set on nearly at right angles with the shaft, whilst all the long bones of the skeleton are hollowed out internally for the reception of the marrow, there can be no doubt as to the terrestrial habits of the animal.  The skull (fig. 180) was of large size, four or five feet in length, and the jaws were armed with a series of powerful pointed teeth.  The teeth are conical in shape, but are strongly compressed towards their summits, their lateral edges being finely serrated.  In their form and their saw-like edges, they resemble the teeth of the “Sabre-toothed Tiger” (Machairodus), and they render it certain that the Megalosaur was in the highest degree destructive and carnivorous in its habits.  So far as is known, the skin was not furnished with any armour of scales or bony plates; and the fore-limbs are so disproportionately small as compared with the hind-limbs, that this huge Reptile—­like the equally huge Iguanodon—­may be conjectured to have commonly supported itself on its hind-legs only.

The Cetiosaur attained dimensions even greater than those of the Megalosaur, one of the largest thigh-bones measuring over five feet in length and a foot in diameter in the middle, and the total length of the animal being probably not less than fifty feet.  It was originally regarded as a gigantic Crocodile, but it has been shown to be a true Deinosaur.  Having obtained a magnificent series of remains of this reptile, Professor Phillips has been able to determine many very interesting points as to the anatomy and habits of this colossal animal, the total length of which he estimates as being probably not less than sixty or seventy feet.  As to its mode of life, this accomplished writer remarks:—­