M ALACOPTERYGII. 213 



Tribe I. Taeniosomi (Lophotiformes). 

 Sub-order 11. OPISTHOMI. 



12. PEDICULATI (LOPHIIFORMES). 

 13. PLECTOGNATHI (BALISTIFORMES). 

 Tribe A. Sclerodermi. 



,, B. Gymnodontes. 



The old group Physostomi (with a ductus pneumaticus to the air- 

 bladder), which is sometimes referred to in the preceding pages, 

 included, roughly speaking, the Malacopterygii, Oslariophysi, 

 Symbranchii. Apodes, Haplomi, Heteromi (in part), and Perce- 

 soces (in part), of the above classification. 



Sub-order 1. MALACOPTERYGII (SALMONI-CLUPEIFORMES)- 



Soft-rayed fishes with the anterior vertebrae simple, unmodi- 

 fied, and without auditory ossicles ; symplectic present or absent ; 

 opercular bones distinct ; pharyngeal bones simple above and 

 below, the lower not falciform. Pectoral arch suspended from the 

 skull ; mesocoracoid always well developed. Maxillary bone 

 forming part of margin of upper jaw ; no barbels. Supra- 

 occipital sometimes separated from the frontals by the parietals. 

 Gills 4, a slit behind the fourth. Air-bladder if present with 

 a pneumatic duct. Dorsal and anal fins without true spines. 

 Pelvic fins abdominal, sometimes absent ; scales usually cycloid, 

 sometimes ctenoid ; occasionally absent. No developed photo- 

 phores. Adipose fin present or absent. This sub-order of 

 Teleostei is nearest to the Ganoids. 



Fam. 1. Leptolepidae. Extinct. Upper Lias to Lower Cretaceous; 

 vertebral centra nearly complete, pierced by the notochord ; without 

 fulcra ; scales cycloid. Leptolepis Ag., Thrissops Ag. 



The Pholidophoridae (p. 180), Oligopleuridae (p. 182), and the Archaeo- 

 maenidae, all extinct, are placed here by Smith Woodward and Boulenger. 



Fam. 2. Mormyridae.* Body and tail scaly ; head scaleless ; upper 

 jaw formed by the two premaxillaries which are fused, and by the maxil- 

 laries. Sub- and very small inter-operculum present ; supraoccipital 

 separated from frontals by parietals. On each side of the skull there is a 

 large cavity leading into the interior and covered by a thin bony 

 lamella. They are without pharyngeal teeth. All the fins are well 

 developed in Mormyriis, caudal, anal and pelvic fins are absent in Gym- 

 narchus. No adipose fin. Pectorals directed upwards. Pseudobranch 

 absent, gill-apertures reduced to a short slit. Air-bladder simple, com- 

 municating with the ear. Two pyloric caeca. A series of pores along 



* Kolliker, Bericht v. d. zootom. Anstalt zu Wurzburg, 1849. Hyrtl, 

 Denkschr. Akad. Wiss. Wien, 1856, xii. p. 1. ErdL, Munchner Gelehrte 

 Anzeigen. Boulenger, Poissons du Bassin du Congo, 1901. 



