Review and Book Notice. 391 
of the disc are pushed the ends of the respiratory organs. 
What a wise provision it seems, to have left that central hole, 
and yet after all, if I mistake not, the breathing organs have 
lost their function! Three days’ rest, and the pupa pushes off 
the disc, swims to the surface, where in a moment out bursts 
the perfect fly to join his fellows in the air. The female fly lays 
about ninety eggs in a jelly mass, 1 m.m. in diameter, attached 
to moss just below the water. The development of the larva 
can be watched through the transparent egg shell, and in six 
days the larva hatches out. 
The newly hatched larve are but specks, and quite trans- 
parent. They differ from the older ones in not having five pairs 
of plumed bifurcating hairs arising from the sides of the body. 
Yet these minute creatures, which I have myself hatched out 
from egg masses placed in moving water, as described above, 
build little mud tubes with arms and nets just as their elders do. 
They are, however, so small as to be scarcely visible without a 
magnifying glass. 
Another species, very closely related to C. puszo, makes a 
still more graceful dwelling. The tube of this larva is shown 
in Fig. II., and has lately been described and figured by Dr. 
Lauterborn, who found it very plentiful in the Speirbach and 
Helmbach, above Lambrecht (Palatinate). The two larve 
resemble one another so closely, that when taken from their 
cases, it is almost impossible to distinguish the species. I 
mention this larva because I have found it moderately plentiful 
in the same streams where Chzronomus pusio is so abundant. 
And as the two larve live together in Devon, there seems no 
reason why this latter should not also be found in the same 
locality where C. puszo was originally discovered, or in other 
places in the north where moorland streams exist. 
as 
Handbook to the Roman Wall, by the late J. C. Bruce, edited by 
R. Blair. Andrew Reid & Co., Newcastle, 1907. 284 pp., 2/6 net. In view 
of the extraordinary interest attached to the Roman wall, the glorious 
country it traverses, and the unique character of the discoveries that have 
been made at different points along its course, it is surprising that it is not 
visited by a far greater number of people. Bruce’s Handbook has done 
much to popularise this magnificent relic of our early rulers, and the fact 
that it has recently reached a fifth edition alone speaks for its value. Seeing 
that the original author is no longer with us, perhaps no better qualified 
person could be found to revise and bring the handbook up to date than the 
energetic editor of the Society of Antiquaries of Newcastle, Mr. R. Blair. 
Since the fourth edition was issued in 1895 many important excavations and 
discoveries have been made along the wall—notably the great camp at 
Housesteads and the discovery in Cumberland of a fragment of a wall of 
turves ; of these Mr. Blair gives good account. The guide is well illustrated, 
and has an excellent folding map. 
1907 November 1. 
