176 On the Reproduction of Deep-sea Fishes. 
preserved eggs did not, of course, float, but their general 
character indicates that they were pelagic. Their distinctive 
size and absence of an oil-globule may render them recogniz~ 
able if procured by tow-net. 
The following is the list of these deep-sea fish :— 
1. Macrurus fasciatus . . . Pelagic. 
porallelus.. =, . ..- Pelagic. 
. Malacocephalus levis. . . Pelagic. 
- Dathygadus sp.) s ) jn, (xen elaee. 
. Allocyttus verrucosus . . . Pelagic. 
Caultodus sloanei . . . . Pelagic? 
. Catetyx messiert . . . . Viviparous. 
. An unknown species . . . Demersal. 
The first five of these have eggs which were found to float 
upwards when placed in a tube of sea-water. Their specific 
gravity, as indicated by their rate of ascent, does not appear 
to be less than that of the eggs of ordinary shallow-water 
fishes, and much less than that of some—e. g., Agriopus. 
Do such eggs ultimately float to the surface before hatching ? 
From observed facts, there seems no reason why they should 
not. The rate of ascent was about 10 seconds in 6 inches, 
or 100 fathoms in 33 hours. The eggs of a common Cape 
fish (Chrysophrys globiceps) were observed to hatch out 
4924 hours after fertilization; they are, however, small, 
being 0°89 mm. in diameter. The larger egg (12 mm. in 
diameter) of the Cape red gurnard (7Zrigla kumu) hatched 
out 77 hours after fertilization. There is presumably time, 
therefore, for pelagic eggs of some deep-sea fishes to reach 
the surface before hatehing takes place. It is to be remem- 
bered, however, that, though these eggs floated upwards in 
water taken from the surface, they may not do so in water 
under great pressure, and the conditions at great depth may 
be such that, while the increased salinity prevents them from 
sinking to the bottom, the great pressure may increase their 
specific gravity to such an extent that they do not float 
further upward, but remain suspended in mid-water. 
Another line of evidence which tends to support the first 
supposition is the fact that the smaller forms of pelagic fish 
are found towards the surface. However this may be, we 
may, from the cases cited, draw other and more justifiable 
conclusions. 
Of the eight fishes mentioned, six have pelagic eggs (with 
one doubtful exception), one is viviparous, and one has 
