32 PISCES. — GAXOIDEI. 



HB. Dorsal fins two, tlic anterior spinous; teoth incisor-liko. 



Balistto-ie, 90. 

 li/i/i. Dorsal fin single, of soft rays only. 



J-J. Snout tulxilar, bearinj? tin; short tonthlp<is jaws at iho cnil ; body 



niailid Syhunatiiiu.I'^ 43. 



EK. Snout not tubular. 



/'. Body clonpate, pcl-shapcd ; maxillarios nncl prpmnxillnrios oonlos- 

 cent with vomer anil palutine.-t. 

 G. Lower jaw projertinfj ; skin covorod with linear imViedded 

 scales arranged at right angles witli each other. 



A.Nr.triT.i.iD.K. 40. 

 GG. Ix)wer jaw not projecting; skin scalclcss. . . Echkliu.k, 41. 

 FF. Body not eel-shaped. 

 II. Breast with a suckiug-disk. 



I. Skin smooth Lii-ahiiud.k, 77. 



//. Skin warty Cvt loi'TEKiu.k, 7S. 



////. Hreast witiiout sncking disk. 

 J. Teetii in each jaw continent into one. 



A'. I$ody compressed, the skin rough Molid.k, 93. 



A' A'. Body not compressed, armed with spines. 



DioDONTin.«, 92. 

 JJ. Teeth in each jaw confluent into two. Tetuaouontid.e, 91, 

 A A. Gill membvanes free from tiie isthmus. 



L. Vent at the throat; vertical tins separate. . . AMnLYorsm.E, 36. 

 LL. Vent normal. 



M. Caudal fin wanting; body naked Tiuciiiriiin.E, 54. 



M.\f. Caudal tin present. 



N. Upper jaw j)rod need in a sword Xiimiiih.k, 52. 



NX. Upper jaw witiiout sword. 



O. Body ovate, much com])ressed Stijomatkid.k, 58. 



00. Body oblong or elongate; gill membranes not united. 

 P. .laws toothless, the lower projecting . Ammodytid.e, 49. 

 PP. Jaws with teeth, the lower not projecting. OniiDiin.K, 87. 



Series GAN0IDI:I. (The (Ianoio Fishes.) 



Tlic name Gannitlci was first usJt'ii by Agassiz for tliosc fislics 

 which are armed with bony i)latc.<*, instead of regular cycloid or 

 ctenoid scales. Later, Johannes Miiller, one of the preatest of 

 pysteinatic zoolo;;ists, restricted the proiip to those fishes which 

 show more or less distinct reptilian or batrachian aflinities, and 

 especially alhnitics with the mailed fishes of the Devonian and 

 CarboniftToiis ages. The pronp is a iH'terojjencoiis one, and one 

 practically scarcely susce|ttible of definition. Some of the (ianoids 

 are clo.sely allieil to the Tdcosts ; some ap|)roach the lUpnni, and 

 some again resemble the Ilnlncpphnli. The existence of the solid 

 optic chiasma, the presence of s«'veral valves in the arterial bidh, 

 and of a iniTi' or Ir^s (]i-vf|(i|ici| spir.il \aivf in the ri-rtiim. di-iin- 



