852 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 



and on the ventral surface. Snout somewhat projecting, with three 

 multifid spines; a ridge armed with spines across front of eyes over 

 top of snout; four of these spines larger than others; rostral tentacle 

 club-shaped, trilobate at tip; width of mouth equal to distance between 

 centers of eyes. Head 2.^; width of disk 2. D. 1-6; A. 4; C. 8; P. 

 14; V. 5. Deep water off southern New England. [Goode.) 

 (Goode, Proc. U. S. Nat. Mus. 18S0, 467.) 



Obdee w.-plectognathi. 



{The Plectognaths.) 



Scapula suspended to the cranium by a posttemporal ; premaxillaries 

 usually coossified with the maxillaries behind, and the dentary bones 

 with the articular; pharyngeal bones distinct; posttemporal coossified 

 with the epiotic and undivided ; interoperculum a slender rod ; suj^erior 

 pharyngeals laminar, usually vertical and transverse; skin with rough 

 scales or covered with shields or spines, sometimes naked; skeleton 

 incompletely ossified, the vertebrae 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 Acanthopteri, its nearest rela- 

 tives being the Chwtodontidcc and the Acanthuridce. (r>i£xr^;c, braided or 



plaited; yvddoe;, ydW.) 



(Plectognatln Giinther, viii, 207-320.) 



ANALYSIS OF FAMILIES OF PLECTOGNATHI. 



a. Jaws with distinct teeth. 

 b. Ventral fins obscdete. 

 c. Teeth narrow; body with an immovable carapace of hexagonal plates; no 



spinous dorsal Ostraciid^e, 127. 



cc. Teeth incisor-like ; body with scales or movable plates; spinous dorsal present. 



BALISTID35, 128. 

 aa. Jaws each modified into a sort of beak, without distinct teeth ; no spinous dorsal. 



d. Body little compressed ; vertical fins distinct TetkodoxtiDvE, 129. 



dd. Body much compressed; vertical fins more or less confluent around the tail. 



Okthagouiscid^, 130. 



Family CXXVIL— OSTRACIID^. 



{Tlie Trunk- jisjies.) 



Body short, cuboid, triquetrous or pentagonal, covered by a carapace 

 formed of firmly united six-sided plates, 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-opening a nearly 



