ON THE ANATOMY OF AMPHIOXUS LANCEOLATUS. 393 



to suppose the Lancelet to have been developed from the dorsal 

 aspect, the seat of its respiration to be transferred from its in- 

 testinal tube to a corresponding portion of its skin, and ganglia 

 to be developed at the points of junction of one or more of its 

 anterior spinal nerves, and inferior branch of its second pair, 

 to have a true annulose animal, with its peculiar circulation, 

 respiration, generative organs, and nervous system, with supra- 

 cesophageal ganglia, and dorsal ganglionic recurrent nerve. 



As some fishes undergo metamorphoses after leaving the 

 ovum, the question naturally suggests itself, is the Lancelet an 

 adult fish ? May it not be the young of some fish in one of 

 the stages of growth ? The uniformity of every specimen of it 

 hitherto described, and the peculiar toughness and firmness of 

 its tissues, appear to be decisive of its being a perfect animal. 



In regard to the zoological position of Amphioxus, Mr. 

 Yarrell was correct in giving it the lowest place in the class 

 of fishes ; but if the details of its structure, and the anatomical 

 considerations which this paper contains, be correct, the genus 

 can no longer be retained in the same family with Petromyzon 

 and Myxine, but will assume an ordinal value in any new 

 arrangement of the class. 



If genera allied to Amphioxus are at present in existence, 

 they are probably not numerous ; but in the ages which have 

 passed since the development of animal forms commenced, 

 abranchiated fishes may have been more common ; and the 

 paleontologist, when his attention is directed to the subject, 

 may probably be able to refer some anomalous organic remains 

 to extinct fishes of this order. 



St. Petersbourg, vol. x.) In vol. xi. he has given an account of the de- 

 velopment nf Amphioxus. In the Bulletin of the same Academy, vol. xii. 

 18G7, Owsjannikow describes the arrangement and structure of tin- nervous 

 system in A. lanceolatus, which, though differing in some points, yet agrees in 

 others with tin' statements made in the text.— Ens. 



