NICHOLS cS: MURPHY : I.ONO ISLAND SHARKS. 5 
;/'. Dorsal fin low. 
Cair/iarhiiiiis obsriirKS 
III'. Both upper and lower teeth narrow on broader lia.ses. 
CarcharhiiiwA liiiiba/iis 
k' . Teeth not .serrate. Narrow, on broad bases. al)ove ami 
below. 
Aprioiiocioii isodoii 
i' . Angle of mouth with a well marked groove extending 
along one or both jaws ; teeth oblique, not serrate. 
Scoliodofi terrcc-iwvcr 
g' . Head pecidiar in form, — flattened, semicircular or hammer-shaped 
Teeth very oblique. 
o. Head semicircular. 
Sphynia fibiiro 
o' . Head hammer-shaped. 
Sphyrna zyi>;ccna 
f . Caudal fin ver\- long, not much, if any, shorter than luad and 
body taken together. 
Alopias vnlpcs 
i'' . Teeth narrow, with basal cusps. Dorsal fins subequal in size. A 
rather small, usually spotted shark. 
Cair/iarias taiirus 
d' . Caudal peduncle with a central keel. Caudal fin more or less lunate. 
p. Gill slits measuring '2 the depth of the body, or 
less. 
(/. Teeth slender and shar]), without serrations. 
r. Origin of the dorsal behind the axil of the 
pectorals. 
Isiinis dekayi 
r' . Origin of the dorsal over the axil of the 
pectorals. 
Isurus punctaiiis 
q' . Teeth triangular, serrate. A ver}- large, iierce 
species. 
Carcharodon cair/iarias 
p' . Gill slits exceedingly long, measuring much 
more than y, the depth of the body. A very 
large, sluggish species. 
Cetorhinns niaxiiiius 
c' . Anal fin absent. Dorsals each with a spine. A small s];ecies usuall\ 
spotted with white. 
Sqiialus ac ant/lias 
a' . Front of pectoral fin separated from the con.stricted neck l)y a deep notch. .\ 
peculiar flattened form. 
Squalina squaiiiia 
