8 SPHYNIDJ^. RENICEPS. 
25 
the middle line of tlie hack, ending in a pit at the root of the tail ; pec- 
'toral fins rather large; ventrals small. Color gray ; candal fin with a 
conspicuons narrow blackish edge. Xewfi^nndland to South America ; 
common southward. Size rather small. 
{Squabis (Carchariaii) terra^-iiovw Richarilson. F. It A. iii, ‘289: Carc'inriaK tcrra’-uww 
Giintlier, viii, ^OC.) 
P^AMiLY VII J. — SPHYRNIDvE. 
{The Ha^imer-headtd Sharhs.) 
General characters of the Galeorhinidw^ but the head si ngnlarly formed, 
kidney-shaped or “hammer ’’-shaped from tie*, extension of its sides, the 
nostrils being anterior and the eyes on Ihc' sides of the “hammer”; 
month crescent-shaped, nnder the “hammer” ; the teeth of both jaws simi- 
lar, oblique, each with a notch on tiie ontside near the base ; no spira- 
cles; last gill-opening over the pectorals; first dorsal ami imctorals 
large, the dorsal nearer pectorals than ventrals ; second dorsal and anal 
small ; a pit at the root (d‘ the candal i candal fin with a single notch 
ti^mid its tip, its lower lobe developed. Genera 3 ; species o ; iidiabiting 
most seas. Large sharks, known at once by the singnl.ir form of the 
head. {Car char lidiv^ part: gron|) Zygardna Giinther, 3<S0-383.) 
* Nostrils near the eyes. 
a. Nostrils simple, wilh the frontal grooves rncliinentaiy or obsolete ; head reni- 
I'orm, ifs anterior and lateral margins oonliueut, forming a semieirele. 
Rkniceps, 2'2. 
lui. Nostrils with grooves extending in front toward the middle of the head; 
liead truly hammer-shaped Sphyrxa, 28. 
22.— RENICEPS Gill, 1861. 
Bo nnet- h ead ed Sha rks. 
(Gill, Ann. Lye. Nat. Hist. N Y. 1861, viii, p. 112; type Squalux iibiiro L.) 
Head reniform, the anterior and lateral margins continent, forming 
a regnhir semicircle, the posterior margins of the sides of the hammer 
very short; nostrils close to the eyes, with the grooves indistinct. 
(Latin, rena, kidney ; ccp.v, head.) 
J51. IS. tillmo’O (L.) Gill. — Shovel-head Shark ; Bonnet Head. 
Body rather slender, not mneh compressed ; head depressed, semicir- 
cular in front, reniform, the itosterior free margins short, the lateral mar- 
gins continnons with the anterior; i)ectorals large; first dorsal high, 
midway between jiectorals and vein I'als ; second dorsal mnch smaller, 
inoduced behind, higher and shorter than anal ; ventral fins moderate ; 
caudal moderate; mouth small, crescentic; teeth small, very oblique, 
with a deei> notch on the onter margin. Color uniform ashy, paler 
