858 PROFESSOR W. C. MSINTOSH AND MR E. E. PRINCE ON 
(opposite the anus) being larger than the others. Five pairs occur behind the yolk-sac, 
while a sixth exists in front of its posterior border. These organs are not opposite each 
other, but the left is a little in advance of the right. The marginal fin is not deep, and 
extends a short distance on the yolk. Very fine cells are visible on its surface. 
The young fishes are somewhat delicate in confinement, the oldest example reared 
in the laboratory being represented in Plate II. fig. 18a—about nine or ten days after 
hatching. The yolk-sac has now shrunk considerably, and the snout projects forward as 
a blunt process. The surface of the yolk-sac anteriorly in one example is minutely 
papillose, but this is probably an abnormality. The pectoral fin is well developed, and 
the eye is slightly silvery. The mere change of these young fishes from a deeper to a 
shallower vessel sutices to cause distress, with speedy opacity and death. 
Ammodytes tobianus, L.—Young sand-eels were found during the Trawling Expedi- 
tions in great numbers about the middle of April,* and they are similarly met with 
annually in St Andrews Bay, generally at a depth of 4 fathoms. 
The youngest form associated with the sand-eel was procured in the mid-water net on 
the 29th March, and measured 6 or 7 mm. in length. The body is slender and elongated, 
while the head is large and bluntly rounded in front. The mandible projects considerably 
beyond the premaxillary region when the mouth is widely open. The pigment of the 
eyes (in spirit) is black, and scarcely a trace of the silvery sheen is noticeable. The eyes 
closely abut on the front margin of the snout. The notochord passes straight backward 
in the centre of the tail, which has only the fine and symmetrically arranged embryonic 
fin-rays. The delicate marginal fin had been injured, and only a remnant existed in front 
dorsally. The pectorals are largely developed. The anus opens about the end of the 
middle third of the body. Black pigment-specks are distributed along the ventral 
surface, viz., a single line from the pectorals a short distance backward, then a double 
line (on each side of the gut) to the anus. Behind the latter a very closely dotted line 
extends to the base of the tail. 
A large number of larval forms similar to the foregoing, though somewhat longer 
(9 to 11 mm.), abounded in St Andrews Bay about the beginning of April, but their 
identity is at present uncertain. 
What appears to be the next older stage (between 8 and 9 mm.) was captured on the 
14th April. The marginal fin (which occurs all round) shows no differentiation, but the 
increase of the hypural elements and the true fin-rays inferiorly cause a slight upward 
bend of the tip of the notochord. A single dotted line of pigment passes from the 
pectorals to the tip of the tail, and a series of large pigment-corpuscles exists on each side 
of the alimentary canal in the middle third. The eyes now show a slightly silvery sheen, 
The mandible is still prominent. Cartilaginous rays occur in those parts of the dorsal and 
anal fins behind the vent. The pectorals are very large, much larger proportionally 

* Moprus and Herncoxe give the spawning season of A. lanceolatus, according to BLocu, in May, and mention that 
Mato found a female with enlarged ova in June. A. tobianus, again, is said to spawn in summer (7.¢., from May to 
August). 
