Marvels of the Universe 947 
In the Frilled Shark, which represents the primeval shape of these fishes, it will be noticed the 
mouth forms a cleft at the extreme apex of the head, which forms a flattened cone. In the Whale 
Shark the mouth is similarly at the extreme end of the snout, and this species is of sluggish habits, 
and feeds only on small fishes. According to some, indeed, it lives largely on seaweed. This, 
however, is probably a mistake. The small size of its teeth, anyway, show that it is harmless enough. 
Thus, then, it is more than probable that our interpretation as to the significance of the shape of the 
head in the typical Sharks is correct. 
SAW-FLIES 
BY FRED ENOCK, F.L.S. 
Tue family of Saw-flies is a very large one, and, unfortunately, they all come under the head of 
insects that are more or less injurious to vegetation. 
The caterpillars are gregarious in their habits, and it is no uncommon sight to the observant 
naturalist to see on various trees, or in the hedgerows, broods of these peculiar grubs, sometimes 
fifty or sixty feeding within quite a small compass of leaves, which they soon reduce to bare ribs 
—passing on to another spray, to repeat the process of defoliation until the shrub is sometimes quite 
disfigured by their depredations. 
The form of the caterpillars is quite distinct from that of ordinary butterflies and moths. The 
first thing that strikes one is the uncomfortable way in which they cling to the edge of a leaf when 
Loy cred Knock, F.LS. 
THE WILLOW SAW-FLY. 
Many of the British Saw-flies are more or less gaily coloured. Some are deep violet, others of a metallic green, and others 
are banded with red and yellow, while all have beautifully iridescent wings. They vary in expanse of wing from three-eighths 
of an inch to two inches and a quarter, 
