334 PETRIFACTIONS AND THEIR TEACHINGS. CHAP. III. 



of reptiles distinct from the Megalosaurus, Iguanodon, Gonio- 

 pholis, and other saurians, whose maxillary organs are known. 

 Before the jaw of the Iguanodon was recognised, I thought it 

 probable this fragment might belong to a species of that genus, 

 and under this impression, I communicated a description, 

 with figures, to the Royal Society, in 184 1. 1 Professor Owen 

 (" Brit. Assoc. Reports," 1842) expressed his opinion that the 

 fossil in question might, with greater reason, be ascribed to the 

 Hylaeosaurus. Subsequent observations have led me to con- 

 clude that it is generically distinct, and in my Memoir on the 

 Jaw of the Iguanodon (" Phil. Trans. 1 " 1848, p. 183), I pro- 

 posed to distinguish the reptile to which it belongs by the 

 name of Regnosaurus? with the specific appellation Northamp- 

 toni, as a tribute of the highest respect and regard to my 

 deeply lamented friend the late noble President of the Royal 

 Society. 



This specimen is a portion of the right side of the lower 

 jaw, three inches in length, and If of an inch in the vertical 

 direction, at the proximal end. It consists of the middle 

 portion of the dentary bone, and the distal part of the oper- 

 cular. It contains the lower third of the fangs of fifteen 

 teeth, and the imprints of three others, with indications of 

 the germs of four successioiial teeth. The fangs are cylindri- 

 cal, | of an inch in diameter, and six occupy the space of 

 one inch ; all the crowns are broken off, some close to the 

 margin of the parapet, others low down in the socket ; and 

 this must have taken place before the jaw was imbedded 

 in the strata, for the sandstone filled up all the sockets, 

 and there were no traces of teeth in the surrounding block. 

 The dentary bone forms a strong parapet ; its inner as- 

 pect is deeply sculptured with the alveoli, to which the 

 fangs of the teeth are anchylosed, in the same manner as in 

 the Iguanas ; but the partitions which separate the teeth are 

 very regular : the germs occupy the same relative position at 

 the base of the mature teeth as in those reptiles. There are 

 indications of a thin mesial alveolar process, but its extent 

 cannot be determined, and it seems probable that the fangs of 



1 " Phil. Trans.," 1841, PI. V. p. 131. 



2 Sussex Saurian. The County of Sussex was anciently inhabited by 

 the Regni. 



