OF THE MARSIPOBRANCH FISHES. 
453 
to rise to a higher platform ; yet, full of metamorphic force, they have spent their 
energy on the old low level; they are, as it were, highly modified Ammocoetes, doomed 
to much morphological arrest, and to some degree of degradation of parts, once promising 
a higher development. 
A study of their development will show whether these suggestions are true or 
untrue. 
List of Abbreviations. 
N.B.—Many of the abbreviations are the same as in Part I. ; the following are 
additional. 
ao. 
Aorta. 
al.s. 
Alisphenoid. 
bp. 
Buccal pouch. 
br.a. 
Branchial artery. 
br.c. 
Branchial canal. 
br.p'. 
Branchial folds. 
c.tr. 
Cornu trabeculae. 
e.ba. 
External branchial aperture. 
ex.br. 
Ex tra -bran chial. 
ex.hy. 
Extra- hy al. 
i.b.a. 
Internal branchial opening. 
i.v.s. 
Intervelar shelf. 
l.d.m. 
Lateral distal mandibular. 
11 
Lower labial. 
l.lp. 
Lower lip. 
It. 
Lingual (and labial) teeth. 
m.d.m. 
Median distal mandibular. 
n.a. (and 
v.a.) Neural (or vertebral) ar< 
or.m. 
Orbital muscles. 
o.s. 
Orbito-splienoid, 
o.s.f. 
Orbito-sphenoidal fenestra. 
py. 
Pituitary space. 
s.d. 
Sucking disk. 
u 
Tongue. 
th. 
Thyroid body. 
u.l. 
Upper labial. 
u. Ip. 
Upper lip. 
v.a. (and 
n.a.) Vertebral (or neural) ar< 
3 N 
MDCCCLXXX1IJ. 
