1 1 90 CLASS REPTILIA. 



existing Crocodiles in having an open channel connecting the infra- 

 temporal fossa with the orbit. The orbits themselves are, more- 

 over, usually but slightly smaller than the supratemporal fossae, or 

 only exceed them but little in size ; while there is no preorbital 

 vacuity. The dorsal scutes are rectangular, and may. be arranged 

 either in two or in several longitudinal rows ; while the ventral 

 armour may form either a single or a double buckler, in which the 

 posterior transverse rows of scutes may either imbricate or articulate 

 by suture. The members of this family inhabited freshwaters, and 

 they range in time from the Purbeck (Upper Jurassic) to the Weal- 

 den (Lower Cretaceous), and not improbably also to the Upper 

 Greensand. Nearly all the known forms are European, but one 

 genus which may belong to this family is American ; and the family 

 is probably also represented in the Cretaceous of India. Three 

 subfamily divisions have been proposed, but before discussing these 

 we may allude to the genera Suchosaurus of the English Wealden, 

 and Hyposaurus of the Cretaceous of North America and Brazil, 

 which not improbably belong to this family, although their precise 

 affinities are not yet satisfactorily determined. The type of the 

 former genus is of very large size, and has the teeth greatly com- 

 pressed ; while in the latter the posterior teeth are of this type, but 

 the anterior ones are rounded like those of Goniopholis, and the 

 symphysis of the mandible is elongated. 



The first subfamily, or Petrosuchince, is very imperfectly known, 

 and is represented only by the genus Petrosuchus, of the English 

 Purbeck beds, in which the posterior nares are placed near the 

 middle of the skull, as in many of the Tekosauridce, and the orbits 

 are considerably smaller than the supratemporal fossae. The 

 cranium itself is of moderate length. 



The members of the second subfamily, or Gojtiopholidince, have 

 the posterior nares placed more posteriorly than in the preceding 

 group ; while there are two longitudinal rows of dorsal scutes ; and 

 the ventral buckler is divided, with the transverse rows of scutes in 

 the posterior portion articulating by suture. In the first, or Longi- 

 rostrine, section of this subfamily the skull is elongated like that of 

 the existing Gharial ; the nasals do not reach the nares, the splenial 

 bone enters into the mandibular symphysis, and the teeth are 

 numerous, and all nearly similar in size. It is represented only by 

 Pholidosaurus {Macrorhy?ichus) of the German and English Weal- 

 den. In the Brevirostrine section, on the other hand, the skull is 

 short, like that of the true Crocodiles, the nasals sometimes reach 

 the nares, the splenial enters but very slightly into the symphysis of 

 the mandible, and some of the teeth are much larger than the 

 others. The dorsal scutes present the peculiarity of articulating 

 with one another by means of a peg at one angle which fits into a 



