XEMATOGXATHI. 
95 
ized Pbysoclistous Teliosts, yet all the subordinate characters disappear 
as we approach the point of union of the two groups, leaving only the 
presence of the air-duct as the ultimate distinctive character of the 
PliysostoMi. In view of this inosculation of the two groups, many 
writers (following Professor Gill) have unitAl them both into one order, 
Teleocepliali^ after the exclusion of various aberrant members of each. 
The retention, in some form, of groups emphasizing the difference be- 
tween the spinous and the soft-rayed fishes seems to us very convenient. 
(Order iVi^so.sfonu Giintlier, v-viii.) 
AXAiYSIS OF ORDERS OF PUYSOSTOMI. * 
A. Pnecoracoid arch present. 
B. Symplectic bone none ; pterotic simple ; anterior vertebr® ’^vith ossicula audi- 
tus 5 supraoccipital and parietals co-ossified j maxillary imperfect, 
forming the base of a barbel; no snbopercfnlum . . XEMAXoax atttt^ K. 
BB. Symplectic bone present. 
C. Anterior vertebriB co-ossified and with ossicula auditus. 
Plectospoxdyli, L. 
CC. Anterior vertebrie similar, distinct, without ossicula auditus. 
ISOSPOXDYLI, M. 
AA. Prtecoracoid arch none. 
D. Scapular arch suspended to cranium ; a symplectic bone ; pterotic 
and anterior vertebrae simple ; parietals separated by supraoceipital. 
Haplomi, X. 
DD. Scapular arch free behind the cranium; parietals in contact; no 
symplectic; maxillary bone lost or connate Exchelycephali, O. 
Oedek K.-NEMATOGXATIII. 
{The Cat-fishes.) 
Parietals and supraoccipital confluent. Four anterior vertebrm co- 
ossified, and with ossicula auditus. Xo mesopteiygium. Basis crauii 
and i)terotic bone simple ; no coronoid bone. Third superior pharyn- 
geal bone wanting, or small and resting on the fourth ; second directed 
backwards. One or two pairs of basal branchihjmls ; two pairs branchi- 
hyals. Subopercnlum wanting. Premaxillary forming mouth border 
above. Interclavicles i)resent. Xo scales. Skin naked or with bony 
plates. 
“ This division is the nearest aUy to the sturgeons {Chomlrostei) among 
Physostomous fishes, and I imagine that future discoveries will jjrove 
that it has been derived from that division by descent. In the same 
After Cope, Trans. Amer. Phil. Soc. 1870, 452. 
