W. S. MacLeay on the Natural Arrangement of Fishes. 203 



The families of Pleuronectina are probably as follow ; but they are 

 rather stirpes than families : — 



ABERRANT GROUP. 



L CYCLOPTERIDiE. Discoboli, Cuv. Ventrals united under throat. 



2. ECHENEIDiE. Ventrals separate. 



3. ANGUILLIDiE. Apodes, Linn. Ventrals none. 



NORMAL GROUP. 



4. GADIDiE. Gadides, Cuv. Symmetrical body, with jugular ven- 



trals far apart from anal fin. 



5. PLEURONECTIDiE. Platessa, Cuv. Body not symmetrical, 



having the ventrals generally a 

 continuation of the anal. 



Many genera of these families of Pleuronectina are wanting, so that 

 I can only guess the above to be the natural series. Brotula and 

 Macrourus certainly show the affinity of AnguillidoB to Gadidce. The 

 affinity of Siluridce to Anguillidce is well known, so that we next pass 

 thus to the tribe CLUPEINA, which are Malacopterygian fishes with 

 abdominal ventrals, i. e. the same as the group called Abdominales 

 by Cuvier. We are now more truly on the ground of your ' Mono- 

 graph on Indian CyprinidcE,' and I have little doubt of the following 

 being really and truly the families or stirpes of the tribe CLUPEINA, 

 viz. : — 



ATHYLA CENTERA. Intestinal canal not furnished with caeca. 



1. SILURIDtE. Silurides, Cuv. No true scales on body; repre- 



senting PLAGIOSTOMI. 



2. CYPRINID^E. Cyprinoides, Cuv, Body scaly, mouth slightly cleft; 



representing CYCLOSTOMI. 



3. ESOCIDzE. Esoces, Cuv. Body scaly, mouth widely cleft ; re- 



presenting LOPHOBRANCHII. 



TH YLA CENTERA. Intestinal canal furnished with caeca. 



4. CLUPEID^E. Clupe^e, Cuv. No second dorsal ; representing 



OSTINOPTERYGII. 

 SALMONIDtE. Salmonides, Cuv. Second dorsal adipose ; repre- 

 senting STURIONES. 



I am often afraid of trusting myself to Mr. Swainson's method of 

 drawing analogies between things in themselves wide apart. A per- 

 son may reasonably doubt the legitimacy of any comparison between 

 a fish and an insect, or even between a fish and a bird ; because he 

 may attribute all such resemblances to the imagination, the objects 

 being in themselves so very dissimilar in every leading point of view. 

 But no one can doubt that a fish may legitimately be compared with 

 a fish, and every one will I think see that there is no effort of the 

 imagination at work when a Silurus is compared with a Chiloscyl- 

 Hum, a Cobites with Cyclostomous fishes, or some of the mailed Eso- 

 cidce with the Lophobranchii. The Clupeidce represent the Ostino- 

 pterygii typically in form, so that I have no doubt you will discover 

 the analogy, as yet unknown to me, which exists between the Sal- 

 monidcc and Sturiones. I was ignorant of the true arrangement of 

 Cyprinidcc until I read your valuable Monograph. I have now no 



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