FISHES-SPINACIDAE— ACANTHIAS. 
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edge is strong, the inner edge being finely serrated towards the base. The foremost teeth con¬ 
stitute a group, are hook-shaped, with a broader base. The adjoining ones are provided exte¬ 
riorly with one or more lateral prongs. The outermost teeth are like those at the lower jaw. 
The body is elongated and fusiform, with a conspicuous lateral line. There is hut one dorsal 
fin, situated between the ventrals and the anal, and partly opposed to the latter. Caudal fin 
with a small lower lobe emarginated towards its extremity, the posterior margin being oblique 
or straight and truncated. The caudal grooves or furrows are wanting. The intestinal valve 
is helicoid. 
Stn .—Notidanini, Bonap. Syst. Vertebr. 1837, 45; &, Selach. Tabul. analyt. 1838, 4. 
Notidani, Mull. & Henle, Syst. Beschr. Plagiost. 1841, 80— Mull, in Wiegm. Archiv fur Naturg. 1845,1, 137.— 
Bd. Iconogr. Encycl. II, 1850, 242.— Dum. Ichthyol. analyt 1856, 133. 
Notidanidae, Owen; Lect. Comp. Anat. Vertebr. Anim. 1846, 51. 
When the branchial apertures are six on either side we have the genus Eexanchus ; and when 
seven of them exist, the genus Heptanchus {Heptranchias) . These were the only two genera 
of the family described by ichthyologists. 
A shark of this family having recently been observed in the hay of San Francisco, California, was 
erroneously erected into a third genus, under the name of Notorliynclius, which does not differ 
from Heptanchus. We will therefore record the species under the appellation of 
HEPTANCHUS MACULATUS, Gr r d . 
Stn. — Notorliynchus maculatus, Ayres, in Proc. Cal. Acad. Nat. Sc. I, 1855, 72. 
In the absence of specimens we forbear drawing up a specific description, and refer our readers 
to the above quoted “ Proceedings of the California Academy,” in which Dr. Ayres has recorded 
the observations he has traced from nature. 
Family SPINACIDAE, Owen. 
The sharks which constitute this family exhibit two dorsal fins, whilst the anal is wanting, 
either dorsal being provided with a strong spine at its anterior margin, as is likewise the case 
in Cestraciontidae. The spiracles are extant, and the five branchial apertures situated in ad¬ 
vance of the pectoral fins. The nictitating membrane of the eye is wanting. The intestinal 
valve is helicoid. 
Syn. — Spinaces, Mull. & Henle, Syst. Beschr. Plagiost. 1841, 83.— Mull, in Wiegm. Archiv fur Naturg. 1845, I, 135 
& 137.— Dum. Ichthyol. analyt. 1856, 133. 
Spinacini, Bonap. Syst. Vert 1837, 4. — Bd. Iconogr. Encyl. II, 1850, 242. 
Spinacidae, Owen, Lect. Comp. Anat. Vertebr. Anim. 1846, 51. 
Some of the representatives of this family are commonly known under the names of “ Dog¬ 
fish” and lc Picked Dog-fish,” both in England and in America, being distinguished from Mus- 
telidae, which go under the same vernacular appellation on this side of the Atlantic, by the 
presence of a rather strong spine at the anterior margin of the dorsal fins. 
ACANTHIAS, Disso. 
Gen. Char. —Head depressed. Outline of the mouth in the shape of a very open curve; a large groove at either angle. Two 
cartilaginous folds of the lips anteriorly (superiorly) and one posteriorly (inferiorly) . Spiracles very large, situated behind and 
somewhat above the eyes, and provided within with a swelled flap arising from their anterior margin. Orbits elongated; upper 
and lower teeth cutting, the edge being nearly horizontal and the point directed outwardly. The root of the tooth is more 
