126 



HULLETIN OF THE I'NITEU STATES FISH COMMISSION. 



Sl'MMAin <»!•' rilE 1''(>UE(J(»IN(S COMI'AUISONS. 



1. T\n' ViUiitU', . I npcnticr transmontiiu US hii"^ a iiiiixiiiiiiiii of 7 iiinii^ tlursal ijiys 

 than iiiiy (»f the Atlantic spccirs. 



2. In tlie VntostoiitltUv, wc have tli(> fjcuiis Xi/niiiclini with I to 2 inoio rays tlmn 

 any of tlic Atlantic {,'i'neiii of (latostDiniiKr an<l the jicnns (JatoHtomus with sl»('(ll^ 

 havinj; 2 more (h)isal rays than any of the Atlantic species of the same frenus. 



.$. lnth(^ ('yiniiivla\ Lepitlomola ami Mnlx ditfer from all other American specio 

 in the (leveiojjment of spines in the dorsiil lin. The <;enera Arrocliciliis, Lnrinia. 

 Poiionichtlu/s, (Hid, and the snbj;enera h'iclitirdsoiiius, S(iualiiis, and Cliroiida all luiv. 

 more rays than then- Atlantic^ relatives. The <;reatest absohite piin in the nund)er i<\ 

 rays over all Atlantic slope spcieles amounts sometimes to S rays. To offset this w. 

 have only some sjieoies of A^«>^>v>/;/,s' and Notcm'ujonm with rays exceeding the usual 

 number on tlie I'acilic slope. In this family both the modilications are found. 



4. In the Sahiionithv, the species of the ;jenus Onotrliyiichun have 13 to 17 anal r.iy> 

 while thehij;host number in the Atlatitic species leaches no more than 11 rays. 



Tlu/inaUiis, on the other hand, has a larger number of dorsal rays than any otlici 

 Anu'rican salmonoid. 



■~>. In the PercopNiihv, tlie fecbh', armature of PercnpHix is ehaiiged into the stnui; 

 spines of (JoUtmhla. 



(5. In the (rdsteroxtrida; I'l/fiosteiis hrachi/podK and (ittnttroxfciis irillioinsoiii linw 

 each 1 more dorsal spine than any of their Atlantic contjeners. 



7. In the Cvntianh'uUv we have an absolute gain ot 1 dorsal spine over iii 

 Atlantic slope genera, while the gain is 2 dorsal spines and I anal spine in ArchopliU 

 as compared with its nearest relative AiHhloplifrs. 



5. Finally in the Cottithv, ('off us ((sper reaches a higher number of dorsal spiin 

 and rays and of anal rays than is ever reached in the numerous Atlantic slope spccii 

 of this genus. Tlui average number of dorsal spines is I more on the L^aeitie slii|i. 

 than on the Atlantic slope, while the average number of anal rays is higher by 2. 



These data fully warrant the statement made at the beginning of this chapteitli 

 " almost every family of tishes havii g representatives in the fresh waters of both lii 

 Atlantic and the I'aeilic slopes has one or more of its representatives modified in on 

 or the other of two directions: Tiiere is either a larger number of rays or spinc> ;: 

 the tins, or some of the rays have become modified into spines.'' 



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