THE FISHES OF POETO EICO. 
285 
This fish attains a length of 5 or 6 inches. Until now it has been known only from the type 
collected by the Albatross in the Gulf of Mexico. We obtained a single specimen, 5.5 inches long, 
dredged at station 6070, in Mayaguez Harbor, January 20, in 225 fathoms, on rocky bottom. 
Peristedion gracile Goode & Bean, Oceanic Ichthyology, 473, pi. cxiv, fig. 387, 1896, Gulf of Mexico, in 142 fathoms, lat. 
28° 82' 30" N., long. 85° 52' 30" W., at Albatross station 249: Jordan & Evermann, 1. c., 2179, 1898. 
Family LXV. CEPHALACANTHIDAi. The Flying Gurnards. 
Body elongate, subquadrangular, tapering behind; head very blunt, quadrangular, its surface 
almost entirely bony; nasals, preorbitals, suborbitals, and bones of top of head united into a shield; 
nuchal part of shield on each side produced backward in a bony ridge, ending in a strong spine, which 
reaches past front of dorsal; interocular space deeply concave; preorbitals forming a projecting roof 
above jaws; preopercle produced in a very long, rough spine; cheek and opercles with small scales; 
opercle smaller than eye; gill-openings narrow, vertical, separated by a very broad, scaly isthmus; 
pseud obranchise large; gillrakers minute; mouth small, lower jaw included; jaws with granular teeth; 
no teeth on vomer, or palatines; scales bony, strongly keeled; 2 serrated, knife-like appendages at base 
of tail; first dorsal of 4 or 5 rather high flexible spines, first 1 or 2 spines nearly free from others; an 
immovable spine between dorsals; anal and second dorsal short, of slender rays; caudal small, lunate; 
pectoral fin divided to base into 2 parts, anterior portion about as long as head, of about 6 rays, closely 
connected; posterior and larger portion more than twice length of head, reaching nearly to caudal in 
adult (Dactyloplerus) , touch shorter in young ( Ceplialacanthus ), these rays very slender, simple, wide 
apart at tip; ventral rays i, 4, long, fins pointed, their bases close together, the inner rays shortest; air- 
bladder with 2 lateral parts, each with a large muscle; pyloric cseca numerous; vertebrae 9 -)- 13 = 22. 
Inhabitants of the warm seas; the adult able to move in the air like the true flying-fish, but for shorter 
distances. One genus. 
Genus 132. CEPHAL ACANTHUS Lacepede. 
Characters of the genus included above. Two species known, the following and the East Indian 
Cephalacanthus spinarella. 
240. Cephalacanthus volitans (Linnaeus). Flying Robin; Bat-fish; Volador; Murcillago. 
Head 4.33; depth 5.5; D. ii-iv, 8; A. 6; P. 28 + 6. First 2 dorsal spines free, slightly connected 
by membrane at base; preopercular spine reaching beyond base of pectoral, not to end of occipital 
spine; pectoral reaching nearly to base of caudal in adult, very much shorter in young; in the young 
the spines of head are much longer. 
Color, greenish-olive and brown above, of varying shades; below pale, marked irregularly with 
dusky and bright brick-red, varying to a salmon- yellow; pectoral fin mottled with bright-blue streaks 
near the base and blue spots and bars toward tip, the under side glaucous-blue, edged with darker; 
caudal fin with about 3 brownish-red bars; coloration extremely variable. 
