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the pigment of the "body, but the caudal patch had spread out in a 
characteristically fan-shaped manner (PI. XVI. fig. 21), coincident with the 
development of embryonic rays in the tail, and the yellowish tint of the 
marginal fin in the same region had somewhat increased. The caudal 
region of the marginal fin seemed to be somewhat less. They are hardy 
larvse, and could without much difficulty be reared in large numbers in a 
suitable enclosure. 
8. On the Development of the Sail-Fluke (Arnoglossus megastoma). 
The earlier writers do not appear to have seen a ripe sail-fluke, or 
'megrim,' as it is often called by the Scottish fishermen. No mention of 
the subject again is made by Parnell or Couch. Day observes that 
' Thompson on 31st October at Belfast procured one which had just shed 
' its ova, only a few mature ones remaining.' Raffaele * pointed out that 
the ova of Arnoglossus have a single oil-globule, and his figure generally 
resembles the egg of the present species, except that he does not allude to 
the minute structure of the zona. His figure, however, of the larval 
Arnoglossus (Zona 4, fig. 20) differs materially from that of a A., megastoma 
both in structure and coloration. Whether the figure of the careful 
Italian author refers to A. latema or other form, however, is unknown. 
Dr Raffaele finally represents the post-larval Arnoglossus with a long ray 
like a flagellum anteriorly. 
Mr Holt,t who found ripe forms of both sexes in March, April, and 
May, states that the eggs are very translucent, and, like those of the brill, 
have a single oil-globule (diam. "30 mm). The diameter of the ova is 
from 1*08 to 1*13 mm. He thinks, from his observations off the west 
coast of Ireland, that spawning takes place only in moderately deep water, 
or in very deep water, and necessarily therefore at some distance from 
shore, always at a great distance from the coast, when the declivity is very 
gradual. On the eastern shores of Scotland the species is an inhabitant 
of the deeper water. 
Three series of ova were received from Aberdeen, viz., two on the 24th 
May, and the third on the 28th May. The first two were both dead, one 
having been fertilized on the 21st May, and the second that morning 
(24th). The former had a diameter of 1*1430 mm., and the clear, colour- 
less oil-globule about *25 mm., and the latter a diameter of 1*2192 mm., 
and the oil-globule "3048 mm. The third series reached the laboratory 
on the 28th May at 11.30, at an early stage of development, and had a 
diameter of D1430 mm., while the oil-globule had a diameter of '3048 
mm. All the living eggs were remarkably buoyant, and had a perivitelline 
space. 
The capsule (PI. XVI. fig. 1) in this species conforms to the type seen 
in the brill and lemon-dab, being covered with raised lines or ridges, with 
very fine striae between them. When viewed from the outside under a 
high power, the capsule (zona) presents the usual minute punctures densely 
dotted over the surface. The micropyle is difficult to distinguish, but it 
appears to be sometimes situated in the centre of a radiate series of lines 
in a space, bounded by other ridges (PI. XVI. fig. 10). It is best seen by 
setting several eggs together on the bottom, so that they support each 
other, and give special positions not seen when each is free. 
On the 29th May (next day) the rim had either reached the equator or 
had extended beyond it (PI. XVI. fig, 2), and a dimple was often present 
on each side (in optical section) where the rim constricts the yolk. The 
* Le uova galleggianti, Mit. a.d. Zoolog. Stat, zu Neap, viii, Bd. i. Heft. 1888. 
Sep. Abd. p. 49, &c. 
t Report of Council, Roy. Dub. Soc. 1891, p. 238. 
