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XV. On the Anatomy of Amphioxus lanceolatus ; Lancelot, YARRELL. By JOHN 

 GOODSIR, M. W.S., Conservator of the Museums of the Royal College of Surgeons 

 in Edinburgh. 



(Read 3d May 1841.) 



THE genus Amphioxus was instituted by Mr YARRELL for the reception of a 

 singular little animal which he received from Mr COUCH. The characters of this 

 genus, as given in the History of British Fishes,* are, " Body compressed, the 

 surface without scales, both ends pointed ; a single dorsal fin extending the whole 

 length of the back ; no pectoral, ventral, anal, or caudal fins ; mouth on the under 

 part of the head, narrow, elongated, each lateral margin furnished with a row of 

 slender filaments." 



My attention was particularly directed to Mr YARRELL'S description of the 

 Lancelet, by an announcement by my friend Mr FORBES, at the Newcastle Meet- 

 ing of the British Association, of the capture of two specimens on the Manx coast. 

 With his characteristic liberality, that gentleman has put these two specimens into 

 my hands, with a request that I would employ them for the purpose of drawing 

 up a detailed account of the animal. 



Unwilling to mutilate both, I have confined my dissections to one of the in- 

 dividuals, and have been fortunate enough to detect its leading anatomical pecu- 

 liarities, to verify most of the observations of the anatomists who have preceded 

 me in the investigation, and to correct what appeared to me to have been errors 

 in their observations. To complete the history of the Lancelet, however, an ex- 

 amination of it when alive in sea- water must be undertaken. In this way only, 

 can certain points in its structure and actions be explained, and light be thrown 

 on the economy of one of the most anomalous of the vertebrated animals. 



The first notice which we have of the Lancelet is in the Spicilegia Zoologica 

 of PALLAS,| wno received his specimens from the coast of Cornwall. Although 

 he observed its ichthyic characters, he allowed himself to be misled by its other 

 peculiarities, and particularly by the membranous folds of the abdomen. He de- 

 scribed it well, but placed it in the genus Limax, under the designation Limax 

 lanceolatus. 



Professor JAMESON has directed my attention to the first volume of STEWART'S 

 Elements of Natural History,}: in which the Lancelet is described as a, Limax with 



* YAURELL'S History of British Fishes, vol. ii. page 468. f PALLAS, Spic. Zool. x. p. 19. t. i. fig. 11. 

 t STEWART'S Elements of Natural History, 2d ed. vol. i. p. 386. 



VOL. XV. PART I. 3 X 



