CLASS PISCES. 



the Purbeck, the length of the upper jaw exceeds that of the lower, 

 and in advance of the mandibular symphysis there is a predentary 

 bone (not shown in the figure) apparently corresponding to the one 

 found in certain Dinosaurs. In Belonostomus, which, as now re- 

 stricted, ranges from the Lower Kimeridgian of Bavaria to the 

 Chalk, the predentary bone is so much elongated as to make the 

 upper and lower jaws of nearly equal length, and the predentary 

 carries a median row of large conical teeth, flanked by two rows of 

 minute teeth • the teeth of the normal bones of the jaws having 

 mammilated crowns adapted for crushing. 



Family Belonorhynchid.e. — This family name has been pro- 

 posed by Mr S. Woodward for the remarkable genus Belonorhynchus, 

 typically occurring in the Upper Trias of Carinthia, but also found 

 in the Lower Lias of Dorsetshire, where the specimens had been 

 originally referred to Belonostomus. According to the writer quoted, 

 Belotiorhynchus was allied to the latter genus, having a similar long 

 and slender body, with the same general position and structure of 

 the fins, and probably furnished with a predentary bone. The fulcra 

 of the fins were, however, either absent or very minute ; and, with 

 the exception of a median dorsal and ventral series of scutes, and 

 another series on the lateral line, the body was naked. The im- 

 perfectly known Saurickthys, from the Rhaetic of Bristol, is a closely 

 allied, if not generically identical, type. Specimens of the upper 

 jaw show that (as in Belonorhynchus) the bone was covered with fine 

 tubercles, and that the maxillae gave off horizontal palatal plates, like 

 those found in Amphibians and Reptiles. 



Family Lepidosteid^e. — The Gar-pikes of the genus Lepidosteus 

 (fig. 927, a), inhabiting the freshwaters of Northern and Central 

 America and Cuba, agree with the Aspidorhy?ichidcs in the general 

 contour of the body and the arrangement of the fins ; but the 

 rostrum of the skull is much longer, and the tail distinctly hetero- 

 cercal. The scales are lozenge-shaped. The existing genus appears 

 to be represented in the Lower Eocene of France by a species (Z. 

 Maxi7iiiliani) formerly referred to Lepidotus ; and it may also occur 

 in the Upper Eocene (Oligocene), where a species described under 

 the name of Naisia has been referred to it. In North America we 

 have also Pneumatosteus^ from the Miocene, and Clastes, from the 

 Lower Eocene, both being freshwater forms, and the latter also 

 occurring in the Eocene of Rheims. 



Suborder 7. Amioidea. — According to Dr Traquair's classifi- 

 cation, the last and most specialised suborder of the Ganoids is 

 typically represented by the existing Amia and a series of Mesozoic 

 genera approximating more or less closely to the Teleostei. In 

 these forms the paired fins are non-lobate ; the infraclavicular bone is 

 absent ; the operculars are Teleostean ; the branchiostegals have a 



