1889.] Synopsis of the Families of Vertebrata. 855 
ciontidae, Spinacidae, Notidanidae, Lamnidae, Carchariidge, Squat- 
inidas, Rhinobatidae, Pristiophoridae ; {Rajcs) Pristidae, Squatinor- 
ajidae, Rajidae, Trygonidae, Myliobatidae. 
TELEOSTOMI. 
There are four superorders of this subclass, which are dis- 
tinguished by the fins. 
Dorsal, anal, pectoral, and ventral axonosts pre- 
sent, represented by a single element to each 
fin ; Rhipido pterygia. 
Dorsal, anal, pectoral, and ventral axonosts pre- 
sent, the dorsal and anal numerous, the 
pectoral in variable number, articulating 
with numerous well-developed baseosts; 
the ventral axonost single, with numerous 
baseosts ; Crossopterygia. 
Dorsal and anal exonosts as in the last ; no pec- 
toral exonost ; pectoral and ventral baseosts 
elongate, numerous ; Podopterygia. 
Dorsal and anal axonosts present ; no pectoral 
axonost ; pectoral baseosts few and small ; 
ventral baseosts rudimental ; dorsal, and 
generally anal baseosts rudimental or want- 
ing ; axonosts not corresponding with neu- 
ral spines ; Actinopterygia. 
RHIPIDOPTERYGIA. 
Two orders of this superorder are known 
Basseosts present in dorsal and anal fins; pectoral 
fin ? Rhipidistia. 
Basseosts wanting to dorsal and anal fins; caudal 
axonosts present, each one articulating with a 
neural spine ; pectoral fin ? Actinistia. 
To the Rhipidistia belongs the single family of the Tristi- 
<:hopteridae ; and to the Actinistia the Coelacanthidae. 
