388 
E. RAY LANKESTER. 
fore intelligible that the furcal ends of the chitinoid rods 
should gradually pass over into a gelatinous reticular form of 
connective tissue. 
The Supra-pharyngeal Coelom and its Perienteric Extension. — 
I have but little to say in regard to this space. It is suffi- 
ciently obvious in sections, and contains a coagulable fluid. 
It is continued down the plaits or folds of the primary pharyn- 
geal bars, and communicates through them with the coelomic 
space surrounding the branchial aorta, viz. the endostylar 
coelom. Anteriorly it ends blindly, acquiring a considerable 
lateral and at last a ventral extension along the inner walls of 
the epipleura, in the praegenital region of the body. Pos 
teriorly, in the region where the perforations of the pharynx 
cease, it forms a narrow space surrounding the intestine, and 
in the post-atrioporal region expands to a much increased 
proportionate volume. It ceases at the anus, and similarly it 
is not traceable anteriorly beyond the sphincter oris. Its 
relations are seen in the drawing (PI. XXXIV, fig. 1). 
The perivascular space of the dorsal aortae has been alluded 
to above in connection with those vessels. I will merely say 
again' that they appear to me to be real spaces, and not arti- 
facts, and that I have not traced any opening into them. 
They unite when the aortae unite and form a single space. 
The perigonadial coelom is, according to the observations and 
speculations of Kowalewsky, Rolph, and Hatschek, a detached 
downward continuation of the pharyn go-dorsal coelom, carried 
downwards with the down- growing epipleura, and subse- 
quently shut off from the pharyngo-dorsal coelom above. In 
such a section as that given in PI. XXXVI we can see that a 
slight horizontal splitting of the connective tissue would place 
the two spaces in communication. 
The Metapleural Lymph-Spaces. — These and the lymph-boxes 
or spaces of the fin-rays appear to be traceable to the original 
myocoelomic pouches. 
The metapleural lymph-canals are large, well-developed 
spaces, containing coagulable lymph. Their existence has been 
denied by some observers in consequence of the action upon 
