AMPHIOXUS LANCEOLATUS. 
401 
the decision of some doubtful questions, and above all pointing 
out a number of matters in which further observation is 
needed in order to clear up uncertainty. The chief points 
brought to notice are — 
1. The number of the myotomes, of the dorsal fin rays, of 
the ventral fin-rays, of the prseoral cirrhi. 
2. The size and importance of the post-oral tentacles, or 
tentacles of the sphincter oris. 
3. The non-existence of the so-called “ ventral canals ” 
beneath the plaited ventral wall of the atrium. 
4. The actual existence of the metapleura and metapleural 
lymph-canals, but their obliteration during complete distension 
of the atrium. 
5. The actual existence as natural spaces of (a) the fin-ray 
compartments, ( b ) dorsal and ventral intrachordal canals, (c) 
the intraskeletal lymph-spaces of the myotomes. 
6. The structure of the gill-bars and endostyle. 
7. The position and form of the atrio-ccelomic funnels or 
brown-canals, now figured for the first time. 
8. The general form of the body as corrected from distor- 
tion by reagents, and the disposition of parts as shown in a 
reconstructed dissection. 
List of Memoirs referred to. 
1. Muller, Joiiann. — “ Ueber den Bau und die Lebenserscheinungen des 
Brancliiostoma lubricum, Costa, Amphioxus lanceolatus, 
Yarrell,” ‘Konigl. Akad. der Wissenschaften,’ Berlin, 1844. 
2. Bateson, W. — “ The Later Stages in the Development of Balauoglos- 
sus Kowalewskii,” ‘Quart. Journ. Micr. Sci.,’ vol. xxv (Supple- 
ment p. 110), 1885. 
3. Bolph. — “ Untersuchungpn ueber den Bau des Amphioxus lauceo- 
latus,” ‘ Morphol. Jahrbuch,’ Bd. ii, 1876. 
4 . Stieda. — “ Studien ueber den Amphioxus lanceolatus,” ‘Memoires 
de l’Acad. Imp. des Sciences de St. Petersbourg,’ tome xix, No. 7, 
1873. 
5. Langeruans. — “ Zur Anatomie des Amphioxus lanceolatus,” 
‘ Archiv fur Mikroskopische Anatomie,’ vol. xii, 1875. 
6. Schneider, Anton. — ‘Beitrage zur Anatomie und Entwickel. der Wir- 
beltbiere,’ Berlin, 1879. 
