852 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 
and on the ventral surface. Snont somewhat projecting, with three 
niultifid spines; a ridge armed with spines across front of eves over 
top of snont; four of these spines larger than others; rostral tentacle 
club-shaped, trilobate at tip ; width of month equal to distance between 
centers of ej’es. Head 2J; width of disk 2. D. I-G; A. 4; C. 8; P. 
14; V. 5. Deep water off southern Xew England. {Goode.) 
(Goode, Proc. U. S. Nat. Mus. 1880, 4G7.) 
Order W.-PLECTOGN ATH I. 
{The Plectognaths.) 
Scapnla suspended to the cranium a posttemporal ; premaxillaries 
nsnally coossitied with the maxillaries behind, and the dentary bones 
with the articnlar; pharyngeal bones distinct; posttemporal cobssified 
with the epiotic and undivided ; interopercnlnm a slender rod ; superior 
pharyngeals laminar, usually vertical and transverse; skin with rough 
scales or covered with shields or spines, sometimes naked; skeleton 
incompletely ossified, the vertebne in small number; ventral fins re- 
duced to a single spine or wanting; air-bladder without pneumatic duct. 
This group is a modified offshoot from Acanthojiteri, its nearest rela- 
tives being the Chevtodontidce and the Acanfhuridee. (-Aexrw?, braided or 
plaited; jaw.) 
{Plectognaflii Giintlier, viii, 207-320.) ’ 
ANALYSIS OF FAMILIES OF PLECTOGNATHI. 
a. Jaws with distinct teeth. 
h. Ventral fins obsolete. 
c. Teeth narrow; body with an immovable carapace of hexagonal plates; no 
spinous dorsal OsTR.\ciiDiE, 127. 
cc. Teeth incisor-like ; body with scales or movable j)lates; spinons dorsal present. 
BALISTIDiE, 128. 
aa. Jaws each modified into a sort of beak, without distinct teeth; no spinous dorsal. 
d. Body little compressed ; A’ertical fins distinct Tetrodoxtid.e, 129. 
dd. Body much compressed ; vertical fins more or less confluent around the tail. 
Ortiiagoriscid^, 130. 
Family CXXVIT.— OSTRACIIDaE. 
{The Trunh-fishes.) 
Body short, cuboid, triquetrous or pentagonal, covered by a carapace 
formed of firmly united six-sided jilates, the jaws, bases of the fins, and 
caudal peduncle free and covered by smooth skin. Mouth small; each 
jaw with a single series of long, narrow teeth. Gill-openiug a nearly 
