ADDENDA 7-. CARCIIARIID^ CARCHARIAS. 067 
very short, its base straight, slightly oblique. Size much less than 
that of Mold rotunda. Pelagic; occasional oft our Atlantic coast. 
{Tetrodon truncafus Retz. Yet. Ak. Nya Handl. vi, 2, 116: Orthagoriscus ohlongus 
Bloch & Schu. 1801, 511: Orihagoriscus truncafus Gunther, viii, 319.) 
Page G : 
Family BDELLOSTOMATID^E. 
The genera Heptatrema and FoUstotrema may be recognized as con- 
stituting a family {Bdellostomidw Gill) distinct from Myxinukc. 
Page 12. We are indebted to Professor Gill for the following outline 
of a proposed subdivision of the Squali. 
The existing Stpiali apjtear to be naturally divisible into four subor- 
ders, which ditfer, so tar at least as the first three are concerned, in 
many important respects. They may be briefly diagnosed as follows: 
I. OPISTIIARTHRI or CYCLOSPONDYLI. 
Squali with the palato-qnadrate apparatus articulated or connected Avith the post- 
orbital processes of the skull; the mouth inferior; branchial apertures in increased 
number (6 or 7) ; only one dorsal tin. The Kotidanida’ alone exhibit these peculiarities 
in the existing fauna. 
II. PEOARTHRI OR ACRODONTA. 
Squali with the palato-qnadrate apparatus articulated by an extensive surface with 
the preorbital region of the skull ; the mouth subterminal and the forehead declivous. 
The Uetcrodoniidw are the only living representatives. 
III. ANARTHRI OR GALEI. 
Squali with the palato-quadrate apparatus not articulated with the skull; the den- 
tigerous portions moderately developed; the mouth inferior. All the living sharks 
except the Squatinidee, lleterodoniidce, aud Xotidanidee belong to this suborder. 
IV. rhina:. 
Squali with the palato-quadrate apparatus not articulated with the skull; the den- 
tigerous portion advanced forwards; the mouth terminal; and the ])ectorals with en- 
larged anterior basal lobes which are separated by notch-like .spaces from the branchial 
region. The family ot‘ Squatinidee is the only existing family of this suboi’der. 
Page 22, etc. The follotving brief “key” will perliaps facilitate the 
ideutification of the species of Carchat ias, which are at present known 
from oar Atlantic coast: 
a. First dorsal far behind pectoral. (Carcharias) Glaucus 
aa. First dorsal close behind pectoral. 
b. Upper teeth oblique, deeply notched on outer margin. (Platgpodon Gill.) 
OB.SCURU.S.. 
bh. Upper teeth triangular, suberect, scarcely notched on outer margin. {Eulamia 
Gill.) 
c. Snout moderate, its length, from mouth, about equal to breadth of mouth. 
CCERULEUS. 
cc. Snout very short, its length much less than breadth of mouth Platyodon. 
