1890.] Zoology. 481 
According to some the ventral bones are homologous with the ribs of 
other fishes, while the dorsal rods are ‘ flesh bones.” According to 
others exactly the reverse is true. As tests, Hatschek calls attention 
to the fact that the muscles in the body of a vertebrate are divided 
into dorsal (epiaxial) and ventral (hypaxial) portions. In the fishes 
the ribs occur between the hypaxial portions and the somatopleur, 
while the ribs of Batrachia and Amniotes are new structures lying be- 
tween the epi- and hypaxial portions. In the body regions of these 
forms the old fish ribs have disappeared, although they occasionally re- 
appear in the caudal portion, old and new ribs coexisting together. 
Applying this test of position to the structures seen in Polypterus it is 
seen that the first view is the correct one, the dorsal half being the new 
or Batrachian rib. In Batrachia and Amniotes the rib articulates 
with the vertebral centrum by two articular processes which primitively 
represent a forked proximal extremity. Gétte found that the rib in 
its development consisted of dorsal and ventral portions, which dis- 
tally grow together while proximally they remain forked. Wieder- 
sheim compared only the lower portion with the ganoid rib, and re- 
garded the dorsal portion as a new structure. This seems to be nega- 
tived by the conditions found in the Batrachian tail. Hatschek farther 
concludes that the vertebrate skeleton should be divided into somatic 
and visceral portions, and that the former should be further subdivided 
into axial, dermal, and septal portions, the latter embracing the por- 
tions arising in the myosepta. 
The Families of Ribbon-fishes,—In the American NATURAL- 
ist for January, 1887 (Vol. XXI., p. 86), I have given a diagnosis of 
the Tzeniosomi. We have now the data for determining the common 
and comparative characters of the best known and only certain represen- 
tatives of the suborder. For the Regalecidz Prof. Parker’s valuable 
Memoir (T. Z. S., Vol. XII., pt. 1), and for the Trachypteride, a 
lately published monograph by Alexander Week (Studies Mus. Zool., 
Univ. Dundee, Vol. I., pt. 6), furnish the requisite information. 
The differences between the two families are greater than would have 
been anticipated, and necessitate a revision of the diagnosis of the 
suborder. The characteristics may now be expressed in the following 
terms : 
TÆNIOSOMI. 
Teleocephals with the scapular arch subnormal, posttemporal un- 
divided and closely applied to the back of the cranium, bétween the 
epiotic and pterotic, or upon the parietal ; hypercoracoid perforate at 
Am. Nat.—May—6 
