1907.] 



OF THE SUBORDER ALLOTRIOGNATHI. 



639 



blade and with an inner posterior process which is connected 

 with its fellow below the prsemaxillary spines ; maxillary processes 

 typically sliding backwards and forwards on each side of a median 

 keel on the vomer or on the prteethmoid cartilage * ; no snpra- 

 maxillary ; lower jaw composed of dentary, articulare and angulare. 

 Palatine without an anterior pi'ocess for attachment of the 

 maxillary. Vertebral column of solid centra which are co-ossified 

 with the arches. Gills pectinate. Pectoral arch attached to the 

 cranium ; no mesocoracoid ; post-clavicle elongate, of a single piece. 

 Air-bladder without pneumatic duct. Vertical fiiis without true 



Text-fi^. 169. 



pmoc 



pimc 



a 



pmoc. 



pmoc. 



Prsemaxillavies (^mx.) and maxillavies ()«.i\) of Trachjq^terus teenia {a.) and 

 Velifer Jii/pselopfertis {b.), seen from below and from the side. 



spines (except sometimes the first one or two rays of the dorsal) ; 

 pectoral fin with hoi-izontal or sub-horizontal base ; venti-al fins, 

 if present, below or a little behind the pectorals, without spines ; 

 pelvis comprising a pair of erect subtriangular bony plates, inserted 

 in the ligament between the coracoids and sometimes directly 

 articulated with them. 



In addition to the characters given in the diagnosis we may 

 note that all the Allotriognathi have the head without spines oi' 

 serrations, 6 branchiostegals, 4 gills, and well-developed pseudo- 



* In the most specialised member of the group , the Lophotid JSumecicMhys, the 

 mouth is not protractile, and the posterior ends of the praemaxillary processes are 

 attached to the anterior face of the vomer. 



Proc. Zool. Soc— 1907, No. XLIII. 4.S 



