168 TELEOSTOMES | 
well known in the case of Deep-sea Fishes, in their acquir-— 
ing a characteristic shape under the conditions of abyssal 
life. The head region of these forms becomes greatly 
exaggerated in size, and the trunk tapers suddenly away 
toward the tip of the pointed tail. The tissues become 
extremely modified, soft, porous, delicate, often trans- 
parent ; skeletal parts are deficient in lime, and loosely 
articulated. Many organs are retained in curiously unde- 
veloped or aborted conditions ; the vertebral axis is noto- 
—— SS . 
— SS 
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Figs. 1'72-1'74. — Deep-sea fishes. (After GUNTHER.) 172. Paraliparis bathy- 
bius. 640 fathoms. 173. Bathyonus compressus. 1400 fathoms. 174. Notacanthus 
sexspinis. 1800 fathoms, s 
chordal ; gill arches, as many as six (?) in number, may open 
freely to the surface, never enclosed by opercula; sensory 
canals remain as open grooves as in the most generalized 
fishes ; paired fins are retained either in an undeveloped 
condition or are not produced at all. Absence of light has 
been not without its effects ; body colours are usually dark 
and meaningless ; while, on the other hand, when eyes still — 
