AMPHIOXUS LANCEOLATUS. 
403 
drawing is intended to show especially the relation of the pharyngo-pleural 
pouches to the pharyngo-dorsal coelom, the position and relations of the atrio- 
ccelomic funnels (“ brown-pigmented canals ”), and the post-atrioporal exten- 
sion of the atrium as a caecal tube running side by side with the intestine 
as far as the anus. A rod, E, is introduced through the atriopore into the 
atrial chamber, and a second rod, F, is passed from the post-atrioporal enlarged 
coelom through the natural passage into the peri-enteric coelom of the prae- 
atrioporal region. The letters are a , d, d' indicate the parts similarly marked 
in the transverse sections figs. 3 and 4 ; v. marks the folded cut edge of the 
body wall corresponding to the pharyngo-pleural pouches of the primary bars 
of the pharynx. 
Fig. 2. — Diagrams of sections through the lines A B of Fig. 1. 
Fig. 3. — Diagrams of sections through the lines C B of Fig. 1. 
Fig. 4. — Amphioxus lanceolatus viewed from the right side, and 
magnified about five times linear. The animal is represented as nearly as 
possible in its living proportions and shape ; the oral hood and tentacles are 
expanded, the atrial cavity is dilated, and the atriopore open. The drawing 
shows the number of the myotonies, sixty-two (this is probably an exceptional 
number, sixty-one or even sixty being more frequent) ; the number of the 
oral tentacles, the number of the dorsal and ventral fin-rays, the number of 
the gonads, the position of the atriopore and the anus. 
Fig. 5. — Amphioxus lanceolatus viewed from the ventral surface. 
The specimen is the same as that drawn in Fig. 4, and the drawing is intended 
to show especially the plaits of the ventral epipleural surface, the position of 
the metapleura, the double series of ventral fin-rays, and the form of the 
praeoral hood. 
PLATE XXXV. 
Fig. 1. — Untouched sketch of a horizontal section through the region of the 
atrio-coelomic canals. The section is in a plane passing below the notochord 
and just cutting the top of the pharynx and the caecum. It shows the two atrio- 
coelomic funnels, with their widely open posterior mouths and their narrow 
anterior terminations, the left a little in front of the right. 
Fig. 2. — Untouched sketch of a vertical section passing through the two 
atrio-coelomic funnels. The division of the muscular fibres of the myotome 
into two groups, a deeper and a more superficial, is seen on the left side. The 
two sets of fibres are separated by connective tissue, but the distinction does 
not depend, as the lettering would imply, on the direction of the fibres 
themselves but on the arrangement of the groups of fibres; in both groups 
the direction of the actual fibres is essentially longitudinal. 
Fig. 3. — Untouched sketch of the section in which the atrio-coelomic funnels 
were first observed. The Amphioxus had been hardened by Kleiuenberg’s 
