THE DEVELOPMENT OF THE SQUID.

LOLIGO PEALII (LESUEUR).

Fig. 12

	A similar view of an older embryo, with its dorsal surface below.
	The letters of reference have the following significance in all the figures of this plate; a, arms; a/, Posterior or siphonal pair of arms; a", second pair; a"', third pair; e, eyes; er, otocyst; es, eye stalk;/, fins; g, gills; h, branchial hearts; m, mantle; mo, mouth; re, rectum; si, inner siphon folds; si', lateral siphon folds; sm, siphonal muscle; v, velum; y, yolk; y', external yolk sac; y", yolk mass of the eye stalks and head; y"', and y"", yolk masses of the body and mantle.