O22 EDWARD PHELPS ALLIS, JR. 
Figs. 1 to 12. Semidiagrammatie figures of transverse sections through a 51- 
mm. specimen of Hyodon tergisus, showing the myodomic cavities and adjacent 
regions, and selected at intervals between the hind end of the interorbital sep- 
tum and the hind end of the basioccipital. 
Figs. 13 to 18 Similar sections of a 20-mm. specimen of Cottus scorpius. 
Fig. 19 Similar sections of a 3l-mm. specimen of Clinocottus analis. 
Figs. 20 to 23 Similar sections of a 115-mm. specimen of Syngnathus acus. 
Figs. 24 to 29 Similar sections of a 57-mm. specimen of Catostomus occiden- 
talis. 
ABBREVIATIONS 
ab, air-bladder ng, nervus glossopharyngeus 
as, aortal support nocm, nervus oculomotorius 
ba, basioccipital nt, nervus trigeminus 
br, brain ona, orbitonasal artery 
dlp, dorsolateral vertebral process pb. I, pharyngobranchial of first bran- 
ear, parts of membranuous ear chial arch 
ec, external carotid artery pb. II, pharynogbranchial of second 
eff, I, efferent artery of first branchial branchial arch 
arch pf, ramus palatinus facialis 
epsb, efferent pseudobranchial artery php, pharyngeal process 
exo, exoccipital pro, prootic 
hmd, hyomandibula prob, prootic bridge 
hmy, horizontal myodomice membrane ps, parasphenoid 
hy, hypophysis psb, pseudobranch 
ic, internal carotid artery pv, pituitary vein 
ic. a, anterior division of internal car- re, musculus rectus externus 
otid artery res, recessus sacculus 
ic. p, posterior division of internal car- inf, musculus rectus inferior 
otid artery 
ios, interorbital septum 
ja, Jacobson’s anastomosis 
l, ligament 
lda, lateral dorsal aorta 
mda, median dorsal aorta 
rint, musculus rectus internus 
rs, musculus rectus superior 
sv, saccus vasculosus 
syc and sy-c, sympathetic nerve and 
communicating branch from N. tri- 
nab, nervus abducens geminus to N. facialis 
nc, notochord or notochordal space vj, vena jugularis 
nf, nervus facialis vlp, ventro-lateral vertebral process 
