368 THE AMERICAN NATURALIST. [VoL. XXXIII. 
to get entirely out of the trap, they would have to break through 
either all the cranial nerves, if they passed out laterally to the 
nerve cords, or else all the cranial cross commissures, if they passed 
between them. 
In order to make the similarity between the cartilages of Ammo- 
ccetes and those of Limulus more apparent, Gaskell produces two 
of 
pass branches of the hemal nerves. This pei is represented in Gaskell’s diagram by the 
two bow-shaped kean on either side of 
diagrams side by side (Journal of Anatomy and Physiology, Vol. 
XXXII, p. 556). One is a diagram of the cartilaginous skeleton of 
Ammoceetes, the other-is labeled a “ diagram of the cartilaginous 
