FISHES OF HAWAIIAN ISLANDS. 
35 
In the following key we give only those families known to be represented in Hawaiian waters: 
a. First dorsal fin over or behind the ventrals; spiracles present; no nictitating membrane II. Scylliorhinidse, p. 35. 
an. First dorsal fin inserted more or less in advance of the ventrals. 
6. Caudal fin not lunate, its upper lobe two or more times the length of the lower, with a notch below toward its tip; 
sides of tail not keeled. 
e. Tail moderately developed, forming less than one-third the total length; eyes with nictitating membrane. 
d. Dorsal fins without spines. 
c. Head normally formed III. Carchariidse, p. 35. 
ee. Head hammer-shaped or kidney-shaped by the extension'of its sides IV. Sphyrnidse, p. 41. 
cc. Tail exceedingly long, forming about one-half the total length; eyes without nictitating membrane. 
V. Alopiidse, p. 42. 
66. Caudal fin lunate; caudal peduncle with a keel on each side; last gill-opening entirely in front of pectorals; teeth 
large and sharp; size large . VI. Lamnidse , p. 43. 
Family II. SCYLLIORHINID^.— The Cat Sharks. 
Dorsal fins 2, both rather small, without spines, the first more or less behind ventrals; anal fin 
present, usually before the second dorsal; caudal fin rather long, usually with a hasal lobe; tail not 
keeled, and not bent upward. Spiracles present; no nictitating membrane; gill-openings small, the 
last one above the root of the pectorals. Mouth usually broad, with small teeth, several series being 
in junction; teeth each with a median cusp and 1 to 4 small cusps on each side; nostrils near mouth, 
sometimes confluent with it, sometimes provided with cirri. Mucous pores about head numerous, 
especially on lower side of snout. Egg cases large, quadrate, with prehensile tubes at angles. 
Genus 2. CATULUS Smith. 
As here understood, this genus is very close to the European genus Scylliorhinus, from which it is 
distinguished by the separate nasal valves. Gill has further divided the group into Catulus, having 
the nasal valves provided with lobes or grooves, Halxlurus having the nasal valves simple, and Cepha- 
loscyllium, which has a very broad head and the stomach inflatable. The latter group, with possibly 
Halxlurus, is perhaps generically distinct. Catulus differs from Pristiurus in having the scales on the 
upper edge of the tail not much, if at all, enlarged and usually not differentiated from the others. The 
prickles on the body are usually much coarser in Catulus than in Scylliorhinus or Pristiurus. Species 
numerous, usually in rather deep water. The single species known from Hawaiian waters is described 
in Section II of this volume. 
Catulus Andrew Smith, Proc. Zool. Soc. Lond. 1837, 85 ( canicula ). 
Poroderma Smith, 1. e. (africanus). 
Halsdurus Gill, Ann. Lye. Nat. Hist. N. Y. 1861, 407 (burgeri). 
Family III. CARCHARIIDAt. — The Typical Sharks; Manos. 
Sharks with 2 dorsal fins, the first short and high, entirely before the ventrals, the second 
comparatively small, opposite the anal; no spines; gill-openings moderate, the last above the base of 
the pectoral; tail more or less bent upward from base of caudal fin; sides of tail not keeled; eyes with 
nictitating membranes; head not hammer-shaped, the snout being longitudinally produced, as usual 
among sharks; spiracles small or obsolete. Ovoviviparous. 
A large family found in all seas. The species are often closely related and difficult of determination. 
a. Carchariinae: Spiracles present; teeth more or less depressed, with entire or serrate sharp edges. 
6. Root of tail without pit; caudal fin with a single notch Galeus , p. 35 
66. Root of tail with conspicuous pit above; caudal fin with a double notch Galeocerdo, p. 36 
aa. Spiracles obsolete; lower teeth narrower than the upper. 
c. First dorsal fin inserted posteriorly, nearer ventrals than pectorals Prionace, p. 37 
cc. First dorsal inserted anteriorly, nearer pectorals than ventrals. 
d. Teeth all serrate more or less, entire in the very young Carcharias, p. 38 
Genus 3. GALEUS Rafinesque. 
First dorsal opposite the space between the pectorals and ventrals; mouth crescent-shaped with 
teeth alike in both jaws, oblique, notched and serrated; spiracles present, small; nictitating membrane 
present; no pit at base of caudal; caudal fin with a single notch. Tropical seas. 
