DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 917 
The properties of the fluid of the chambers are quite adequate for the development 
of the otoliths toward the internal wall. It is sufficient to point to the growth of the 
Nemertean stylets to prove how perfectly such organs can be produced in successive 
generations of the species. 
On 20th February a considerable increase in the otocystic cartilage of the wolf-fish 
had taken place. From before backward this is marked superiorly by an increase in the 
cartilage behind and above the eye, and inferiorly by a thickening of the bar behind. 
The great development of the cartilage of the basilar plate around the anterior end of the 
notochord gives this inferior bar a more distinctly horizontal position, one of its chief 
flexures being caused, indeed, by the carotid. 
On 16th March the cartilaginous mass anteriorly and superiorly has increased so much 
that it presents a complete ring in section, and thus somewhat further back the cartila- 
ginous boundary is complete externally, while internally it ends abruptly opposite the 
lower border of the optic lobe. It then sinks downward and presents a large perforated 
median prominence below the ganglionic mass of the fifth, by which the auditory 
nerve passes into the cavity. The latter contains large ganglion-cells and hyaline 
coagulable lymph. After this swelling the cartilage diminishes internally, and ends on 
each side of a median mass of connective tissue below the infundibulum. Beneath its 
termination is a space and then an artery and vein (carotid and jugular). The poimted end 
of the notochord begins above this median band of connective tissue. By and by the ear- 
tilaginous floor, now somewhat thin, glides in towards the notochord, and almost coalesces 
superiorly. At this part it forms a thin wall externally, and ends in a thickened region 
about half-way up, and the latter increases from before backward over the posterior semi- 
circular canal, until a complete ring is formed round it, only a slender bar connecting the 
latter inferiorly with the somewhat thickened end at the notochord. The contrast also 
between the massive inner wall of the canal and the thin outer wall is marked. Then 
(proceeding backward) the ring is broken internally, and only a slender line externally 
connects the thickened superior loop with the thin horizontal bar leading to the noto- 
chord. The superior mass diminishes and disappears, and the outer part of the horizontal 
bar becomes disconnected from the denser region at the side of the notochord, the poste- 
rior boundary of the ear being formed by a thickened mass of cartilage jomed to the arch 
over the spinal cord, and again forming a ring, as in front, before terminating. 
A month later considerable change had oceurred in the otocyst—the chief feature 
being the diminution of the cartilage, which is now covered by a layer of hyaline ossific 
tissue, running from the notochord over the floor, and along the thin layer of cartilage 
externally, but the thickened mass to which the hyomandibular is joined does not show 
it distinctly. As soon as the bar becomes nearly horizontal (sloping a little upward and 
outward from the cord), this hyaline coat extends from the cord to the upper and outer 
border of the ear. The three semicircular canals seem to be similar to those in the previous 
stage, but the ganglionic aperture in the floor anteriorly is less distinct, and the ganglion 
lies more completely in it. The head of the hyomandibular is rounded, and the cartila- 
