(SAu?/ o/Gonorliynchus Greyi, 369 



nearest relations are tlie NotopteridEe, but tliey are more 

 remote from Gunorftynchus than is Notopterus itself, and may- 

 be dismissed i'ortliwitli. 



The ;j:cmis Hi/odon, while presenting no eranial characters 

 Mhich would negative the poj^sibility of affinity with Gono- 

 rhi/nchus, affords no affirmative evidence. It retains certain 

 primitive characters which have been lost in Gonorhijnchus, 

 such, for instance, as the bounding of the upper border of 

 the gape by both maxilla and premaxilla, the meeting of the 

 right and left parietal bones, the presence of teeth on the 

 parasphenoid, the continuation of the cranial cavity through 

 the orbitosiihenoid, and the presence of a basisplienoid. So 

 far as the evidence of the characters of the skull bears upon 

 the question, it is not beyond the bounds of possibility tliat 

 Gonorhyndius should have been descended from some 

 ancestral branch of the family Hyodontidse, differing from 

 the modern Hijodon in having a smaller supratemporal, in 

 liaving no air-containing vesicle by the side of the occipital 

 region of the cranium, and in possessing an angular bone 

 distinct from the articidar. 



None of the characteristic features of the Clupeoid skull 

 are met with in Gonorhynchiis. The most striking of such 

 features are the presence of a posterior temporal groove, a 

 temporal foramen, pre-epiotic fossa, auditory fenestra, right 

 and left posterior wings of the parasphenoid, with eye-muscle 

 canal opening between them, and bullate swellings in the 

 squamosal and pro-otic bones for lodging vesicular diverticula 

 of the swim-bladder. No suggestion of any of these is to be 

 found in Gonorhynchus. 



Gonorhynckus was by Valenciennes associated with Chanos 

 because of the large size of the branchiostegal membrane 

 and the absence of teeth. It is true that there are several 

 respects in which Chanos differs from the Clupeidie proper 

 and approaches Gonorhynchus — snch, for instance, as the 

 want of teeth in the jaws, the w^ant of a temporal foramen, 

 pre-epiotic fossa, auditory fenestra, posterior wings of the 

 parasphenoid, and orbitosphenoid and basisphenoid bones, 

 the reduction in size of the mouth, so that the maxilla fails 

 to form part of the boundary of the gape, the absence of 

 surmaxilla;, the separation of the quadrate from the meta- 

 pterygoid, and the reduction in the number of the branchio- 

 stegal rays. But the large size of the posterior temporal 

 fossa and the completeness of its roof are distinctly against 

 the supposition of Valenciennes. 



This last objection applies also to the families Elopidie 



