80 CLADOSELACHIAN SHARKS 
and the writer now finds that an exceedingly simple con- 
dition existed in the neural and hzmal arches ; they prove 
to be of moderate size and thickness, each a tapering rod 
of cartilage, forked at its base; each body segment con- 
tains a single neural and hzemal spine, closely alike in size. 
Unlike modern sharks, Cladoselache was without claspers : 
its eggs must have been fertilized after their deposition, as in 
the majority of fishes other than Elasmosbranchs. The gill 
openings, at least seven (probably nine) in number, appear 
as in the restoration, to have been shielded anteriorly by 
a dilated dermal flap. A spiracle was probably present. 
The jaws were slender, and apparently hyostylic (p. 257) ; * 
the teeth are of the pattern of shagreen denticles, but occur 
Fig. 86 B.— Teeth of (“Cladodus”) Cladoselache:=3%-4. The above forms 
occur in different regions of the mouth. 
in clusters (“ Cladodus,” Fig. 86, B). The mouth was ter- 
minal in its position. The nasal capsule was apparently 
not connected with the mouth by a dermal flap. The eye 
was protected by several rings of rectangular plates, clearly 
shagreen-like in character. The integument was finely 
studded with minute lozenge-shaped denticles, and was 
everywhere lacking in membrane bones. The lateral line 
retained its groove-like character. 
The shark, Acanthodes (Fig. 87), of the Coal Measures 
is now to be regarded (Smith Woodward) as a member of 
a highly specialized Palaeozoic group. And its many spe- 
cialized structures —added to its greatly reduced size — 
* As Claypole’s recent figure seems to demonstrate. Am. Geol., Jan. 1895. 
