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. 



1. CYCLOPTERIDiE. Discoboli, Ci^i'. Ventrals united under throat. 



2. ECHENEID.^. Ventrals separate. 



3. ANGUILLID.E. Apodes, Lin7i. Ventrals none. 



NORMAL GROUP. 



4. GADJDyE. Gadides, Cuv. Symmetrical bod}', with jugular ven- 



trals far apart from anal fin. 



5. PLEURONECTID^. Platessa, Cuv. Body not symmetrical, 



having the ventrals generally a 

 continuation of the anal. 



Many genera of these families of P/ewro«ec^2Ha are wanting, so that 

 I can only guess the above to he the natui'al series. Brotula and 

 Mucrourus certainly show the affinity of AiiyuillidcB to Gadidce. The 

 affinity of SiluridcE to A/iguiUidoi is well known, so that we next pass 

 thus to the tribe CLUPEINA, which are iMalacopterygian 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 Cyprinidc^,' and I have little doubt of the following- 

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

 viz. : — 



ATHYLACENTERA. Intestinal canal not furnished with CEeca. 



1. SILURIDCE. SiLURiDEs, Cuv. No true scales on body; repre 



senting PLAGIOSTOMI. 



2. CYPRINIDyE. Cypkinoides, C«w. Body scaly, mouth slightly cleft; 



representing CYCLOSTOM I. 



3. ESOCIDiE. EsocEs, Cuv. Body scalv, mouth widelv clelt; re- 



presenting LOPPIOBRANCHII. 



THYLACENTERA. Intestinal canal furnished with cseca. 



4. CLUPEID^. Clupe^, Cuv. No second dorsal ; rein-esenting 



OSTINOPTERYGIl. 



5. SALMONID.^. 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 tliat a fish may legitimately be compared with 

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

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

 lium, a Coi/7e.s' with Cyclostomous fishes, or some of the mailed Eso- 

 cidce with the Lophobranchii. The Clupeida; represent the Ostiiio- 

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

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

 monidce and Siurmies. I was ignorant of the true arrangement of 

 Cyprinid(£ until I read your valuable Monograph. I have now no 



P2 



