NEW POINTS IN THE STRUCTURE OF AMPHIOXUS, 257 
On some NEW Points in the StRuctURE of AMPHIOXUS, and 
ther Brarinc on the MorrHotocy of VERTEBRATA. 
By E. Ray Lanxester, M.A., F.R.S., Fellow of Exeter 
College, Oxford, and Professor of Zoology and Com- 
parative Anatomy in University College, London. 
Wirth the assistance of my pupil, Mr. Fanning, of Exeter 
College, I have recently (December to March) prepared alarge 
number of specimens of Amphioxus by means of transverse, 
oblique, horizontal, and vertical sections. The specimens 
were collected by me at Naples in 1871 and some 1874, 
were preserved in absolute alcohol simply, others had been 
previously treated with dilute picric acid (according to 
Kleinenberg’s plan), others had been first of all placed in 
H. Miiller’s fluid. The dissection and slicing of these speci- 
mens was carried on in the histological laboratory of Exeter 
College, but I had also made some examination and drawings 
of Amphioxus in the living state when at Naples. 
Recently attention has been directed to certain points of 
structure in Amphioxus by Haeckel,! by Ludwig Stieda,? 
by Huxley,? and by Wilhelm Miiller.t There is a remark- 
able divergence on many points in the statements of these 
and earlier writers, and whilst awaiting the completion of the 
drawings which Mr, Fanning intends to publish in illustra- 
tion of the anatomy of the Lancelet, I may briefly set down 
some of our more important conclusions. I shall refer to 
the illustrations in the memoir of Stieda (‘ Mém. de I’Acad. 
St. Pétershourg, vii série, tome xix, No. 7. Plates 
I—IV), which, though inaccurate in some important respects 
and deficient in detail, will enable me to make clear my mean- 
ing in the absence of special illustration. 
There are two causes which seem to have led to a diversity 
of opinions in connection with the anatomy of Amphiowus. 
Firstly, the action of the reagents which are used for preserving 
the specimens leads according to circumstances either to an 
excessive distension of cavities, accompanied by the separa- 
tion of membranes which are in the living state adherent one 
to another, or on the other hand the reagent brings about an 
1 Ernst Haeckel, ‘ Anthropogenie,’ p. 667. Leipzig, 1874. 
2 Stieda, ‘‘ Studien ueber den Amphioxus lanceolatus,”? ‘Mem. de l’Acad. 
de St. Petersbourg,’ vii serie, tome xix, No. 7, 1873. 
8 Huxley, “The Classification of Animals,” ‘ Quart.—Jeurn;—Mieros, 
Seience;-Jan., 1874, 
4 W. Miller, “Ueber das Urogenitalsystem des Amphioxus und der 
Cyclostomen,” ‘ Jenaische Zeitschrift,’ vol. ix, p. 94, 1875. 
