MUSEUM OF COMPARATIVE ZOOLOGY. 45 
net, as well as in the trawl and attached to the dredging rope, the 
following are the genera which were noticed by us: Anthemodes, 
Bassia, Agalma, Athorybia, Crystallodes, Nectophysa, Pterophysa, Rhi- 
zophysa, Velella, Porpita, Physalia, Praya, Diphyopsis, Diphyes, Abyla, 
and Cymba. 
Crystallodes and the genera of Diphyes were by far the most common 
of the Siphonophores ; we scarcely made a haul of the tow-net without 
finding some bells or fragments of these two groups. 
The other Acalephs were not numerous in species, although sometimes 
we passed through great numbers of a large species of Liriope, and some 
of the Ctenophores, of which a species of Mertensia and a Mnemiopsis 
were the most common. Ocyroé was observed once, Idya was compar- 
atively rare, and Cunina was found occasionally, while the trawl and tow- 
nets frequently brought up Periphylla, Drymonema, Nauphanta, Atolla, 
Stomobrachium, an /Equorean allied to Tima, genera allied to Saphenia, 
to Melicertum, to Lizzia, and to Cyteis, and a genus allied to Rathkea. 
OBSERVATIONS ON THE Penagic Fauna or THE INTERMEDIATE DEPTHS 
IN THE Panamic DISTRICT, MADE BY THE “ALBATROSS” WITH THE 
Tanner Tow-NET. 
As I stated at the time Chun published the results of his first ex- 
periments, I considered them inconclusive,’ and was of course anxious 
to repeat them in a strictly oceanic district, in great depths, and at a 
considerable distance from shore. 
On Plate L, I have given figures of a slightly modified Chun-Petersen 
tow-net, which was constructed by Ballauf, of Washington, for my use 
on this expedition. 
Figure 1 shows the closed net ready to lower; Figure 2, the net 
opened, ready to tow at the required depth; and Figure 3, the closed 
net on its way up. fis the metal frame protecting the propeller p. The 
propeller shaft extends to the crossbar c”, fitting into a socket from which 
it is relieved after a few turns of the propeller, when the net is first 
moved horizontally, and liberates the rings of the chain b from the bar 
c", and thus opens the jaws of the net, bringing the strain on the two 
parts of the chain a. As soon as the propeller shaft passes beyond the 
crossbar c, the upper parts of the chain a are relieved, and it then 
becomes the longest, and the strain comes upon the chain 5, which pulls 
1 Am. Jour. of Science, 1888, Vol. XXXV. p. 421. 
