EXPLANATION OF THE LETTERING. 477 



iv.op.g Imagination for optic ganglion. 



1 Lacunae; lateral plate; labrum. 



l.ab.m Longitudinal abdominal muscle. 



l.ab.n Longitudinal abdominal nerve. 



la.f . . .Lateral fold. 



l.ch Lemmatochord. 



l.c.n Lateral cardiac nerve. 



l.co. ... ... .Longitudinal connectives. 



l.cord. ... . Lateral cord. 



l.e Lateral ethmoids; lateral eye. 



l.e.n . Lateral eye nerve. 



Ley . . Lateral eye. 



l.ey.g Lateral eye ganglion. 



l.ey.n .Lateral eye nerve. 



l.f .. Lateral fold. 



Ig. Lung. 



Ig.b. or l.b. . . . .Lung book. 



l.h.tr . Longitudinal haemal tract. 



1.1. . .Lateral line of canal organs. 



l.lo. Lateral lobes to the olfactory recess. 



l.l.ch Lateral bands of the lemmatochord. 



1m Lamellae. 



l.m.pl Nerve plexus of longitudinal abdominal muscle. 



l.n. ..... . . Lateral nerve. 



Ins . Lens. 



l.n.tr Longitudinal neural tract. 



l.p Lateral process; lateral subdermal process to the mandi- 



bular plates. 



l.pl . Small bony plates in the fleshy sides of rostrum. 



l.pl.t .... ... .Lateral plastro-tergal muscle. 



l.tr Lateral tracts of brain. 



m . .Mouth; muscles. 



man . Mandibles. 



max .Maxillae. 



m.br . . Midbrain. 



m.c. . . . .Merochord; segment of the lemmatochord; marginal cells. 



m.cd.n . Median cardiac nerves. 



m.ch Middle chord; median nerve; notochord. 



m.cl Mesencoele. 



md Mandibles. 



m.d Mullerian duct. 



mes.c . . Mesocephalon. 



mesen.c.... .Mesencephalon. 



met.c Metacephalon. 



meten.c Metencephalon. 



m.f . . Median furrow. 



m.l .Median line; marginal line of canal organs; mantle layer. 



m.lch. .Median portion of the lemmatochord. 

 m.lo.. . Maxillary lobes. 

 m.m . Muscle markings. 

 m.n Median nerve (mouth). 



