MR GOODSIR ON THE ANATOMY OF AMPHIOXUS LANCEOLATUS. 249 



exhibiting scarcely any dilatation. He perceived a dark point which he supposed 

 might be the rudiment of an eye, but he could observe no cerebral nerves. He 

 saw numerous ribs, but no branchial clefts, and described a large opening at the 

 posterior extremity of the gill-cavity, which he supposed to be a branchial open- 

 ing similar to those in the myxine. 



MULLER'S own observations were made upon Mr YARRELL'S specimen, and 

 also upon two sent to him by RETZIUS. He verified RETZIUS' and SANDEV ALL'S 

 account of the chorda dorsalis, on the sheath of which he perceived circular fibres. 

 The oral filaments he described as consisting of central and tegumentary portions. 

 The black spot or rudiment of an eye he could not detect. He observed the 

 general structure of the branchial cavity, ribs, and vessels, but did not determine 

 the existence of the branchial aperture described by RETZIUS. He states that the 

 intestine terminates anteriorly in a cul-de-sac, a little behind which the branchial 

 cavity opens into it on the left side. He supposed that some glandular streaks 

 on the walls of the cul-de-sac of the intestine represented the liver, and considered 

 a row of glandular masses on each side, consisting of cells containing dusky oval 

 bodies as the ovaries. After some remarks on the structure of the muscles and 

 skin of the Lancelot, Professor MULLER states the necessity for farther observa- 

 tions to ascertain the details of its structure. 



The only specimens of the Lancelot, then, which have been examined are 

 PALLAS' specimen, Mr COUCH'S two specimens, one of which is in the possession 

 of Mr YARRELL, the specimens examined by RETZIUS, SANDEVALL, and MULLER, 

 and the two in my own collection. Two specimens, I believe, exist in the Museum 

 of the Zoological Society of London.* 



Having now stated what has already been done in the anatomy of this re- 

 markable animal, I shall proceed to describe in detail the structure of the speci- 

 men I have depicted, reserving for the concluding part any general observations 



1 may have to make on its structure and zoological character. 



The dimensions and weight of the specimen of Amphioxus which has afforded 

 the materials for this paper, are, length 2 inches ; depth, a little before the middle, 



2 lines ; weight 8 grains. The other specimen in my possession is half an inch 

 shorter, and not so favourable for examination. They were dredged up by Mr 

 FORBES from a sand-bank, in deep water, on the east coast of the Isle of Man, 

 were extremely active, and resembled, on superficial inspection, small sand-eels. 

 On each side of the abdomen are two longitudinal membranous folds, and behind 

 them an anal fin, omitted in Mr YARRELL'S description. The folds commence, 

 minute, on each side of the hyoid apparatus, pass back on the sides of the abdo- 

 men, increasing in breadth till they are as broad as one-fifth of the depth of the 



* Magazine of Natural History, July 1838. 



