XVII ELASMOBRANCHII—-HOLOCEPHALI 473 
were very small and simple. The caudal filament, which is 
longer in older specimens than in the younger, and is not 
developed at all in the youngest examples at present known 
(Fig. 272, A), is not uptilted, although the lower lobe of the 
caudal fin is much larger than the upper. Young forms have a 
double row of stout spine-like denticles in front of the second 
dorsal fin, and also in the interval between the latter and the 
upper caudal lobe. Similar denticles are also present on the 
upper surface of the head between the orbits (Fig. 272). #. 
raleighana is found in the North Atlantic. Individuals varying 
Fig. 272. —Young example of Harriotta raleighana, 4 inches in length. A, side view ; 
B, dorsal view. (From Goode and Bean.) 
in length from 4 to 25 inches have been taken at depths 
ranging from 707 to 1081 fathoms. <A species of Harriotia 
has also been recorded as occurring in Japanese waters.’ 
With the probable exception of Chimaera colliei the surviving 
Holocephali are denizens of deep water; hence their comparative 
rarity and our almost complete ignorance of their habits. Young 
forms of (C. monstrosa, 14 to 5 inches in length, have been 
dredged in the Firoe Channel at depths from 505 to 555 
fathoms ;* and the youngest specimen of Harriotta was obtained 
from 991 fathoms. Egg-cases are rarely obtained, and then 
only from considerable depths. It is therefore reasonable to 
1 Mitsukuri, Zool. Mag. Tokyo, 1895, quoted in Nat. Sci. viii. 1896, p. 10. 
2 Giinther, Chall. Reports, Zool. xxu. 1887, p. 12. 
