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BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Family XXXI 1. HOLOCENTRID^. The Squirrel-fishes. 
Body oblong or ovate, moderately compressed, covered with very strong ctenoid or spinous 
scales. Head with large muciferous cavities; eye lateral, very large; preorbital very narrow; mouth 
moderate, oblique; premaxillaries protractile; maxillary very large, with supplemental bone; bands 
of villiform teeth on jaws, vomer, and palatines. Opercular bones and membrane bones of head gener- 
ally serrated or spinescent along their edges. Branchiostegals 8. Gill-membranes separate, free from 
isthmus. Gills 4, a slit behind fourth. Pseudobranch ire present. Gillrakers moderate; no barbels. 
Sides of head scaly. Lateral line present. Dorsal tin very long, deeply divided, with about 11 strong 
spines depressible in a scaly groove; anal with 4 spines, the third longest and strongest; ventrais 
thoracic, with 1 spine and 7 rays; caudal deeply forked with sharp rudimentary rays or fulcra at base. 
Vertebrae about 27. Pyloric caeca 8 to 25. Air-bladder large, sometimes connected with organ of 
hearing. General color, red. Young with snout sharp and produced (constituting the nominal genera 
Rh ynchi chi h ys, Rhamplwberyx, and Rhinoberyx based on peculiarities of immature examples). 
There are 4 genera and about 70 species of these gayly colored inhabitants of the tropical seas, 
abounding about coral reefs. 
a. Preopercle without conspicuous spine at its angle; air-bladder divided by a contraction, anterior part extending 
to the otocrane : Myripristis 
an. Preopercle with a conspicuous spine. 
b. Suborbital arch armed with 3 long spines curved forward; scales undescribed Plectrypops 
bb. Suborbital arch simply serrated; scale moderate, 38 to 55. 
c. Mouth moderate, its length less than one-half head Holocentrus, 48 
cc. Mouth very large, considerably more than one-half head, lower jaw projecting Flammeo 
Genus 48. HOLOCENTRUS (Gronow) Scopoli. 
Body oblong, moderately compressed, ventral outline nearly straight, back a little elevated, tail 
very slender. Head compressed, narrowed forward. Operculum with a strong spine above, below 
which the edge is sharply serrated; a strong spine at angle of preopercle. Orbital ring, preorbital, 
preopercle, interopercle, subopercle, occiput, and shoulder-girdle with their edges sharply serrate. 
Mouth small, terminal, the lower jaw projecting in adult. In the young the snout is much produced. 
Maxillary broad, striate, with supplemental bone. Eye excessively large. Scales moderate, closely 
imbricated, posterior margin strongly spinous. Lateral line continuous. Dorsal deeply emarginate, 
spines usually 11, depressible in a groove; soft dorsal short and high; anal with 4 spines, first and 
second quite small, third very long and strong, fourth smaller; caudal widely forked, both lobes with 
rudimentary rays spine-like. Ventrais large, i, 7, spine very strong. 
The numerous species of this genus are remarkable for the development of sharp spines almost 
everywhere on the surface of the body. Of the nine known American species, two occur in Porto Rico. 
a. Preopercular* spine long, tapering, acute; third anal spme very long, more than half depth of body. 
b. Mouth moderate, lower jaw extending to below first one-third to one-half length of eye. 
r. Scales small, 48 to 55 in lateral line; upper lobe of caudal longer than lower, falcate; soft dorsal and anal elevated, 
pointed at tip, this character subject to variation ascensiovis, 74 
rc. Scales moderate, about 45; depth of body 2.6 in length; membrane of front spines of dorsal black siccifer 
rcc. Scales rather large, 38 to 42 in lateral line; caudal lobes nearly or quite equal. 
/I. Maxillary extending to below middle of eye. 
c. Depth of body greater than length of head coruscus 
ec. Depth of body equal to length of head brachypterus 
dd. Maxillary extending to below first third of eye; dorsal with black markings vexillarius , 75 
bb. Mouth small, maxillary reaching to below first fourth of eye; upper lobe of caudal longer; cheek with a white 
blotch osculus 
aa. Preopercular spine short, flatfish, notched at tip; third anal spine short, its length about one-third depth of body; 
soft dorsal and anal low, rounded sancti-pauli 
74. Holocentrus ascensionis (Osbeck). “ Candil” ; Squirrel-fish. 
(Plate 3.) 
Head 3.1; depth 3.3; eye 2.8; snout 4; maxillary 2.3; mandible2; interorbital 2 in eye; D. xi, 15; 
A. iv, 10; scales 4-48-7, 6 before dorsal; caeca 25; vertebrae 11 16. Body considerably compressed, 
* Little dependence can be placed on this key, as several species are imperfectly known and of doubtful validity. 
