338 Remarks on the Natural History of Fishes. 



would very naturally be expected of him to whom you have 

 ever entrusted the care of the subjects upon which the work in 

 question treats ; and with this feeling, I have thrown together 

 the following observations, which I now offer without further 

 remark. 



Commencing with the Cartilaginous Fishes, the first ten pa- 

 ges are occupied with the history of two foreign species of Petro- 

 onyzon, neither of which is found in our waters. 



The marinus and fluviatilis should have been Americanus and 

 nigricans ; both of which were accurately described by Le Sueur 

 in the "Transactions of the Philosophical Society" in 1818 — 

 fifteen years before the appearance of this work. These two for- 

 eign species are accompanied by figures copied from the German 

 plates of Struck; and one or two points require to be noticed. 

 It is well known that one of the characteristics of this ge- 

 nus is "its seven branchial orifices." Now it happens, that the 

 engraver of Strack's plates thought that six would suffice, and 

 accordingly omitted one in his figure. The American copy- 

 ist, while he has attempted to exhibit the very attitude of the fish, 

 has carefully followed his original, and the specimen before us is 

 minus a branchial hole. The German did however continue the 

 dorsal fin to the caudal, as is natural. The plate before us repre- 

 sents it as terminating at some distance in front of that fin. 



The plate of the second species exhibits in S track the true 

 number of branchial openings ; this copy has but five ! 



I suspect that foreign ichthyologists will scarcely pardon the 

 presumption which would assert that these two species, which are 

 described as distinct by Linneus, and have been thus acknowl- 

 edged by all succeeding naturalists, " are to all intents and pur- 

 poses the same fish." 



The thirty four following pages contain the order Selachii. 

 In the prefatory remarks to this order, Dr. Smith observes, that 

 the male shark may at once be recognized by the appendages to 

 the ventrals, though he says " their use is totally unknown." 

 Had he consulted standard works on the subject, he would have 

 found that these appendages were called '■'■ clasp ers f and know- 

 ing that the female did not possess them, their use might with- 

 out much stretch of the imagination be inferred. 



Eight species of sharks are here catalogued. The Scyllium 

 canicula and catulus I have never seen, nor heard of, on our coast, 



