7 1 NTTEIBDTIONS TO NORTH AMKL'ICAX ICHTHYOLOGY IV. 



<;n. Art 'rial luill) with a pair of oppo-ite valves; optic nerves not forming a chiasma. 



(Scries Ti:i.;;osn:i.*') 



c. Air-bladder (if present > connected l>y an air-duct with the stomach or 

 nv.oplia.uns: ventral tins (if present) abdominal, llx-ir hasilar segments 

 riidimental, usually without spines; parietal bones usually united. 



PHYBOSTOML 



Air-bladder without duct; ventral fins (if present ) usually thoraeie or 

 jugular, without basilar segment s : spines usually pre.-eiil , at least ill the 

 dor.-al and \entral tins; parietal bones separated by the BUpraoccipital. 



PUYSOCLISTI. 



ARTIFICIAL KEY TO TIIE FAMILIES OF TISCES. 



Tin- following key is intended simply to facilitate the identification of 

 species. N<> at tempt is made to indicate the natural characters or rela- 

 tions of the families, and only those species of any group which occur 

 within the limits of the United States are taken into consideration. 



I._ YKXTRAL FINS PRESENT, ABDOMINAL. 



* Dorsal tins _', the anterior chiefly of soft rays, the posterior adipose. 

 A. Body naked. 

 B. Head with 1 to 8 long barbels; dorsal and. pectoral fins each -with a spine. 



^1I.URID.<E, 29. 

 Bi!. Head without barbels; tins without spines. 



( '. Teeth strong; dorsal tin many-rayed Al.r.nix >s.\ri:ii >.!:, 40. 



'('. Teeth minute; doisal Jin short tSTKUNori vcmuJJ, 43. 



AA. lioily sealy. 



J>. Teeih broad, incisor-like C'IIAIJACINID.U, 32. 



]>l >. Teetli (if Jiresent ) pointed. 



I Margin of upper ja\v formed by the prcmaxillaries alone. 

 ]'. Dorsal tin nearly median. 



( I. J!(idy with phosplioreseeiit s]iots SCOPKLIDJE, 42. 



<'.. I'.ody without jillos]i!loreseent spots. 



II. Head scaly ; scales cycloid ; teeth cardifonn Sc. <ITI n>.r, -J'J. 



IIII. Head nailed ; scales ctenoid ; teeth villiform . . I 'i:i:< MI--I i > i:, -17. 

 FT. ] ial fin posterior; teeth unequal; body elongate.. FABAIJCPID2B:,41. 



]'.!'.. Margin of upper jaw formed by 7iiaxillaries posteriorly. 



.). Body with phosphoresoent .sjiots; gill-rakers none. 



ClIAfl loDONTID.'K, 44. 



.1.1. Body without phosphorescent spots ; j;ill-rak' nt. 



SAI..MONI P.K, -10. 



" " I ' led liy free spines. 



K. Ilody .scaleless, naked or with bony plates. 



I.. Ventral tins J, 1, 1 he spine strong ; MIOII! moderate. 



CAM i BO : ; MM:, <M. 

 1. 1.. \ i ntral fins I, .">, the sjiiiu' slender; snout prolonged. 



AI'I.MI:IIVNI IIIDI:. (i:?. 

 KK. Body scaly ; snout tubular An.i >^ IDMA IID.K, fi'J. 



* 7l'/ Of, )" rl'.'cl ; unr'nn-, bone. 



