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ERIK A : SON STENSIO 
n. glossypharyngeus. The lateralis branch, that has its exit together with this nerve, runs 
quite close to the lateral surface of the opisthotic for some distance in a dprsal direction 
and finally pierces the opisthotic and extends in this way on to the dorsal surface of 
the neurocranium. The posterior semicircular canal, according to Sagemehl (1884, p. 206) 
almost always comes into immediate contact with the epiotic. 
In young specimens of Lepidosteus Veit (1907, pp. 173 — 188) has only found the 
prootic in close connection with the labyrinth. In older specimens, I have found that 
this was also the case with the epiotic and the lateral occipital, both of which were 
pierced by the posterior semicircular canal. While in younger individuals of a long- 
nosed Lepidosteus species I found a rather large cartilaginous interspace between the 
lateral occipital and the prootic, in adult specimens of a short-nosed species of the 
same genus I observed that these bones meet in a suture on the lateral wall of the 
labyrinth region, and, according to Agassiz, the same bone seems to have had a similar 
extension in the large specimen of Lepidosteus osseus investigated by him (Agassiz 1843, 
vol. II, PI. B", fig. 2). In the adult specimens mentioned both of the bones in question 
have grown until they meet each other, and it is noteworthy that in the short-nosed 
species — the only one I had an opportunity of testing with regard to this — n. glosso- 
pharyngeus pierces the posterior part of the prootic. In older specimens the foramen 
vagi is quite surrounded by the lateral occipital. Parker (1882, p. 481) says that he found 
an independent opisthotic, but I was unable to find anything of this sort in the specimens 
investigated by me. In his explanation of fig. 32 1, in «Cyclostomes and fishes» (1909, 
p. 342! Goodrich says that the opisthotic of Lepidosteus may possibly by fused with the 
lateral occipital, a view to which I shall return later on. 
In Polypterus Traquair describes (1871, p. 168), as is mentioned above, only one 
paired substitution bone in the labyrinth region, which he interprets as the opisthotic 
+ epiotic. Traquair also points out that this bone is pierced both by the posterior and 
the external semicircular canals, and that it is also closely related to the sacculus 
(«aids in the support of the otholithic sac»). On the other hand Wijhe (1882, pp. 257— 
258, PI. XV, fig. 6) states that besides this bone he observed a small independent prootic, 
which was intimantely connected with the parasphenoid. Goodrich (1909, p. 295) holds 
a similar view too and considers that the prootic might be fused to the parasphenoid. 
Both Pollard (1892 a) and Lehn (1918) seem, however, to have overlooked Wijhe’s 
statement mentioned above; at any rate they accept Traquair’s view without any 
criticims. Recently Supino (1914, p. i 83 ) has mentioned the occurrence in Calamoichthys 
calabricus Smith of a large prootic, an epiotic and a small opisthotic, so that Wijhe’s 
observations obtain a certain importance. 
With regard to the opisthotic in Polypterus' Allis in 1899 (pp. 55 —56), after 
describing Traquir’s view, makes the following remark, which is very interesting in 
this connection: «It seems to me that it must include not only those two elements, 
which are, respectively, the intercalar and exoccipital of my description of Amia but 
also the so-called primary part of the squamosal of teleosts». It is therefore of great 
importance to know in more detail the relations of the squamosal, the opisthotic and 
the prootic in Calamoichthys, but unfortunately I have not had any opportunity of 
investigating this form and Supino has almost confined himself merely to giving the 
