86 ALLMAN, ON APPENDICULARIA. 
rarely accompanied with the cmgulum. In this case, again, 
we may look forward with some confidence to its being found 
in a living state, parasitic on some of the smaller sea-weeds. 
On the Pecutian Apprenpace of Apprnpicuarsa, styled 
“Haus” by Mertens. By Prof. Artman, F.R.SS. L. &. E. 
(Read at the Royal Society of Edinburgh, December 6th, 1858.) 
WHILE using the towing-net in the Clyde, near Rothesay, 
during the last week of April, 1858, I observed among the 
contents of the net numerous specimens of an Appendicu- 
laria, which I cannot, without some doubt, refer to any 
described species, but which I shall not at present venture 
to name as distinct, for my attention was at the time rather 
turned to other poimts in its economy than to the determi- 
nation of its specific characters. 
In no one instance did any of these specimens present 
traces of the remarkable appendage described by Mertens 
under the name of “haus,”* an appendage hitherto never 
witnessed by any naturalist save Mertens himself. The day, 
however, was bright and the water smooth, and while looking 
into the sea over the side of the boat, my attention was 
arrested by some singular bodies swimming at the depth of 
a few inches below the surface. 
With these bodies I was altogether unacquainted, and my 
efforts were accordingly at once directed to the capturing of 
some of them. In this I soon succeeded by means of a — 
basin carefully introduced beneath them, and to my great 
pleasure I found that I had the identical species of Appen- 
dicularia just taken in the towing-net, but now invested 
with a most singular and elegant appendage, which was 
easily recognised as the “haus” "described nearly thirty 
years ago by Mertens as occurring in specimens of Appen- 
dicularia taken by him in the neighbourhood of Behring’s 
Straits, and never since seen, though thousands of indi- 
viduals of different species of this genus had fallen under the 
observation of such able investigators as Miller, Huxley, 
Leuckart, and Gegenbaur. 
There was no difficulty, however, in perceiving how it was 
* »Mém. de l’Acad. Imp. des Sc. de St. Petersbourg,’ 1831. 
