26 TELEOSTOML 
dd. Vertebre amphiccelian (double concave); maxillary not transversely 
divided; scales cycloid. . . . . + + + Havecomorpuil, X. 
aa, Arterial bulb thin, with a pair of opposite valves; optic nerves crossing, 
not forming a solid chiasma. (Series TELEOSTEL.) 
e. Air-bladder (if present) connected by an air-duct with the intestinal 
canal, this persistent throughout life; ventral fins (if present) abdomi- 
nal, without spines, their basilar segments rudimental. (Soft-rayed 
fishes.) (Physostomi.) 
J. Shoulder girdle attached to the skull by means of a post-temporal bone 
(suprascapula); form not eel-like. 
g. Precoracoid arch, present. 
h. Maxillary bone imperfect, forming the base of a long barbel; no 
subopercle nor symplectic bone ; four anterior vertebre much 
modified, co-ossified, and with an ossicula auditus; supraoccipitals 
and parietals co-ossified; no scales. . . NEMATOGNATHI, XI. 
hh. Maxillary bone perfect, not entering into a barbel (rarely entirely 
wanting); subopercle and symplectic bone present. 
i, Anterior vertebre modified, co-ossified, and with the ossicula 
auditus. . .. + oe + « « « . Eventroenarni, XII. 
tw. Anterior vertebrze stile to the etheen; separate, and without 
ossicula auditus. . . . + « « .  Isosponpyxt, XIII. 
gg. Precoracoid arch obsolete; antoniny vertebre not modified; parie- 
tal bones separated by ‘supraoccipital head scaly. 
Hapiomi, XIV. 
Jf. Shoulder girdle not attached to the skull; no precoracoid arch; 
parietal bones in contact; maxillary wanting or united with the 
palatines; form eel-like.. . . . . . + + . Apopgs, XV. 
ee. Air-bladder without duct (in the adult); ventral fins without basal seg- 
ments, usually anterior in position; spines usually present in the fins; 
pectoral fins not on the plane of the abdomen ; parietal bones usu- 
ally separated by the supraoccipital. (Spiny-rayed fishes chiefly.) 
(Physoclysti.) 
Jj» Shoulder girdle connected to the skull by a post-temporal. 
k. Lower pharyngeals co-ossified; no spines; ventrals abdominal; lateral 
line on side of abdomen. . . . . . . S¥NENTOGNATHI, XVI. 
kk. Lower pharyngeals separate (or united, and the dorsal fin with 
spines.) 
i. Gills tufted; pharyngeal bones and most of the branchihyals want- 
ing; skin with bony plates. . . . . LopHoprancnu, XVII. 
i, Gills pectinate (as usual in fishes). 
m. Superior branchihyals and pharyngeals reduced in number ; 
ventrals sub-abdominal. . . . . Hemiprancutt, XVIII. 
mm. Superior branchihyals and pharyngeals in normal development. 
n, Ventral fins abdominal, . . . . . .  PxrRcesoczs, XIX. 
nn, Ventral fins thoracic or jugular. 
v. Pectoral fins not pediculate, the gill openings in front of them. 
p. Bones of the jaws distinct. 
q. Cranium normal. . . . . . . ACANTHOPTERI, XX. 
qq. Cranium twisted, so that both eyes are on the same side 
of head; no fin spines. . . HETEROsomAra, XXI. 
