24. CHIM^RID^. 
53 
margins of the disk darker. (Dunieril.) Tropical waters of A.merica; 
north to North Carolina and San Diego. Eeaches a width of about 20 
feet. 
(‘‘Eaia hirostris Walbaum ” : Cephaloptera varnpifrus Mitcbill, Ann. Lyc. Nat. Hist. N. 
Y. 1823, 23: Diaholiclitkijs elliotti Holmes, Proc. Elliott Soc. Nat. Hist. 1856, 39 : Ceratop- 
iera vampyrus Dunieril, Hist. Nat. Poiss. i, 660 : Ceratoplera vampyrus Giinther, viii, 498.) 
Subclass HOLOCEPHALI. 
{The Chimceras,) 
The characters of the single order. * 
Okder e.-holocephali. 
{The Chimceras.) 
Skeleton cartilaginous. Gill-cavity witli four clefts within, but having 
one external opening only, which is covered by a fold of skin, within 
which is a rudimentary cartilag||[j|lj)us operculum. No spiracles. Mouth 
inferior. Jaws without separate teeth, but armed with bony plates. 
Intestines with a spiral valve. No air-bladder. Jaws and palate 
coalescent with the skull. Derivative radii sessile on the sides of the 
basal bones of the limbs, separated from the articulation. Pectoral fins 
normally developed, placed low. Yentral fins abdominal. Tail taper- 
ing. Skin smooth or nearly so ; its muciferous system well developed. 
A single family. 
{Holocephala GiMnihcr, viii, 348-352 ; blog, solid; KS(j)al7i, head.) 
Family XXIV.— CHIM^RID^. 
{The Chimceras.) 
Body elongate, rather robust anteriorly, tapering posteriorly. Head 
compressed. Mouth inferior. Gpper lip deeply notched. Nostrils 
confluent with the mouth, separated by a narrow isthmus. Jaws with 
the teeth confluent into four bony laminm above and two below. No 
spiracles. Males with a iieculiar cartilaginous hook, armed with prickles 
• at the ti)), and turned forward on the upper part the snout. Pectoral 
fins free, placed low. Ventral fins abdominal, niany-rayed, i^rovided in 
the male with claspers. Dorsal fin usually divided ; anteriorly with a 
very strong si)ine, which is grooved behind. Caudal fin low, fold like. 
Skin naked, rarely somewhat prickly. Lateral line present, usually 
with numerous branches anteriorly. Three free gOls and two half gills, 
