CYCLOSTOMATA, LEPTOCARDII. 
127 
CYOLOSTOMATA. 
Petromyzon marinus. Figures of its spermatozoa ; Gulliver, P. Z. S. 
j 1875, p. 336. . 
LEPTOCARDII. 
1^ Amphioxus. Preliminary note on the brain and skull, the absence of 
I which is only apparent, as, though not clearly defined, they occupy a 
/ considerable portion of the cerebro -spinal axis and the vertebral column ; 
/ Huxley, P. R. Soc. xxiii. [1874] pp. 127-131. 
I On the spinal chord ; Moreau, Bull. Ac. Belg. (2) xxxix. pp. 312-329, 
’ figs. 1 & 2, 1 plate. 
On the anatomy ; Hasse, Morph. JB, i. Heft 2, pi. ix. 
On the urogenital system ot^Ampkwxus and the '^ Cyclostomata ; W. 
Muller, Jen. Z. Nat. ix. pp. 94-130, pis. iv. & v. 
On the vent and its lateral position in'^Amphioxus : also on the position 
of the vent in various other fishes ; Wilder, P. Am. Ass. 1874, p. 275. 
