150 Pelagian Mollusca collected on a [no. new series. 
Beagle he alludes to a towing net of " bunting," but he does 
not mention how it was kept open. Not having tried a net with a 
wooden hoop, I cannot pronounce on their respective advantages, I 
observed that with the iron hoop our net was^generally half sub- 
merged, and it would thus probably have more scope for the cap- 
ture of specimens than a net with a wooden hoop, which would 
oftener skim the surface without dipping sufficiently, but the strain 
was very great with the iron hoop as we not unfrequently lost both 
net and hoop. We generally examined our net every quarter of an 
hour as we soon found that when it "was left too long, its contents 
were very apt to be damaged by friction'. 
On the 8th of April in Lat. 29-32 N. Long. 18-56 W. we made 
the first trial of the net, but the speed of the ship immediately tore it. 
For the next two or three days we essayed with nets made of " gunny 
bag," a kind of coarse brown cloth of open texture, but they retain- 
ed too much water and owing to the dark color of the cloth it was 
difficult to see if there was anything in the net ; finally we return- 
ed to the use of white mosquito gauze, the only objection to which 
was, that it too often required to be repaired or renewed. 
April 18th, Lat. 7-6 N. Long. 24-55 W.* At night we pass- 
ed a few PyrosomaSy these animals the most brilliant of noctilucent 
molluscs, belong to the 6th Class or Titnicata, They are cylin- 
drical, cartilaginous bodies, 3 or 4 inches long,open at one end,tuber- 
culated, hyaline or almost transparent; they rise to the surface only 
at night, and although but few were seen on this occasion, yet dur- 
ing a former voyage, when near the same Lat. and Long, our ship 
for eight successive nights passed through countless thousands of 
them. They evidently floated a little below the surface,as we could not 
manage to enclose any in the net, but by means of several large 
fish hooks tied together and dragged astern we were enabled to se- 
cure two fine specimens for examination. When first taken in the 
hand in the dark, they shone like molten metal, in color a pale but 
* Itmustbe borne in mind that the Latitudes and Longitudes mentioned, al- 
ways refer to the actual position of the ship at noon, but by referring to our 
course traced on the accompanying chart, our position at any given time may be 
inferred with sufficient accuracy. 
