dy 4 
1884.] v4 7 [Cope. 
and that the posterior one cannot be said to be within the oral cavity, as 
is the case in the known families of the Dipnoi. It is probable that there 
is a frontoparietal foramen at the posterior bifurcation of the frontal bones, 
corresponding to the conarium or pineal body of the brain. In a cranium 
broken across just anterior to the bifurcation, a canal passing forwards 
and downwards is exposed. There is a foramen, or possibly only a deep 
fossa on each side of the middle line on the occipito-sphenoid suture. The 
foramen magnum is rather small and opens upwards. Its border displays 
no articular surfaces. At the middle of a line connecting the posterior 
borders of the postorbital processes is a small shallow fossa, or probably 
foramen, from this there extends on each side backwards and outwards, a 
shallow groove apparently for a vessel, which terminates at the anterior 
one of three foramina already mentioned as in line with the fissure which 
distinguishes the lateral ala of the basicranial axis posteriorly. A. similar 
groove connects the first and second of these foramina, and in one speci- 
men the groove from the median foramen joins this connecting groove. 
In front of the median foramen is a rather larger one on the median line, 
situated at the fundus of a short longitudinal groove. It is placed just 
posterior to a line connecting the preorbital processes. The grooves easily 
become obsolete by weathering. 
II. AFFInrTins. 
In determining the systematic position of this animal, it will be con- 
venient to take a survey of the characters of the primary divisions of the 
fishes. In 1840 Bischoff published the first account of the osteology of 
Lepidosiren. In this description he called the frontal bones malars with 
a question, and the pariétals frontopariétals. He described the skull as 
having an os quadratum. In 1854, Stannius in the Handbuch der Zod- 
tomie* correctly determined the frontals and pariétals, and stated further 
that the ‘‘lower jaw and hyoid bone articulate directly with continuous 
processes of the chondrocranium.’’ This appears to be the first correct 
description of the cranial structure of the Dipnoi. In 1864,+ Huxley re- 
Stated the view of Stannius as to the nature of the mandibular articula- 
tion ; adopted the opinion of Bischoff that the frontal is a frontopariétal, 
and took a new position in calling the frontals supraorbitals. He also 
restates in general, the description of the skull of the Holocephali already 
given by Stannius. 
The system of Johannes Miiller, adopted by Stannius, was a great im- 
provement over preceding ones. It embraced, however, the error of in- 
cluding the Holocephali in the same sub-class (Elasmobranchi) with the 
sharks, This was adopted by Gill in 1861,{ by Huxley in 1864§ and in 
1871.] All of these authors adopt at these dates the sub-class Ganoidea, 
*Krstes Buch, die Fische, p. 49. 
t+ Elements of Comparative Anatomy, p. 210. 
{Catalogue of the Fishes of the Bast Coast of North America, p. 24. 
? Elements of Comparative Anatomy. 
| The Anatomy of Vertebrated Animals, p. 120. 
