858 The American Natiiralist. [October, 
^'5. No symplectic. 
Anterior vertebrae simple ; a preoperculum and 
palatine arch ; Ichthyocephali. 
yy. Scapular arch free from cranium. 
8. A symplectic bone. 
Hyoid arches developed; Holostomi. 
8<l No symplectic. 
Opercular bones and five osseous branchial arches, 
with ceratohyal ; Enchelycephali. 
Opercular bones, and one osseous branchial arch, 
ceratohyal ; Colocephali. 
No opercular bones, nor ceratohyal, nor osseous 
branchial arches ; Lyomeri. 
The families of the Physostomi are as follows : 
Lysopteri*; Pala^oniscidae. 
Merospondyli ; Sauropsidae ; Pycnodontidae ; Stylodontidae ; 
Sphserodontidae ; Macrosemiidae. 
Halecomorphi ; Amiidae. 
GiNGLYMODi ; Lepidosteidae. 
IsosPONDYLi ; Dapediidae ; Lepidotidae ; Aspidorhynchidae ; Sau- 
rodontidae ; Osteoglossidae ; Heterotidaj ; Galaxiidae ; Clu- 
peidae ; Chirocentridae ; Salmonidae ; Thymallidae ; Alepo- 
cephalidae; Gonorhynchidae ; Sauridae; Lutodiridae ; Au- 
lopidje; Elopidae ; Albulidae ; Hyodontidae ; Notopteridae. 
AcTiNOCHiRi ; Pelecopteridas. 
Plectospondyli ; Characinidae ; Sternopygidse ; Cobitidae ; Cyp- 
rinidae ; Catostomidae. 
ScYPHOPHORi ; Mormyridae ; Gymnarchids. 
Nematognathi ; Siluridae ; Hypophthalmids ; Aspredinidae. 
Haplomi; Esocidae; Stratodontidae ; Umbridae ; Cyprinodon- 
tidae ; Amblyopsidae. 
Glanencheli ; Gymnotidae. 
Ichthyocephali ; Monopteridae. 
Holostomi ; Symbranchids. 
Enchelycephali; Nemichthyidae ; Anguillidae ; Congridae. 
Colocephali ; Muraenidae. 
Lyomeri ; Saccopharyngidae ; Eurypharyngidae. 
