H 
THE NATURALISTS’ JOURNAL. 
Unio. So the swan mussel opened its valves preparatory to 
commencing, and the Unio settled himself in a comfortable 
position, with his single pedal containing his otocyst or auditory 
organ thrust forward so as not to lose a single word. At a 
respectable distance were gathered various representatives of 
different families, all intent on recording every word that fell 
from between the swan mussel’s valves. 
“ Well, then,” she began, “ you must know that when I 
first found myself possessed of life, I was very much unlike 
what I am now. So greatly did I differ that you would not 
have been able to recognise me, and it would have been very 
excusable too. I found myself in company with many 
thousands of others, all like myself, not knowing what we 
were nor wheve we were. Afterwards I found out that we 
were between the gills of a swan mussel, whither we had 
passed from the ovary while we were still in the egg, and I 
was told that there was room in these gills for the accommo¬ 
dation of some three millions of us. Peculiar creatures we 
were too ; each of our valves—for thus early we possessed 
them—was shaped like an equilateral triangle, but the apex 
was incurved and toothed like a saw, which I found very 
useful later on, as I shall show you. We only had one 
adductor muscle in the place of the two which we now 
possess, and the foot—ah ! how different to the shapely and 
fleshy muscular one which we afterwards gained. It was 
scarcely to be called a foot, but from it, rudimentary organ as 
it was, projected a long byssus, which also I found of great 
service. We were nourished during the time we stayed between 
the two lamellcd of the outer gill by a substance formed in the 
gill itself, and-” 
“In my family,” broke in the little squeaky voice of the 
Sphcenum corneum, “ while young we were enclosed in a special 
brood pouch near the inner gill, and we were nourished by a 
secretion from its wails. Sometimes——” 
“ Tut, tut, hold your tongue, child !” said the swan mussel, 
in a testy voice. “ What do you know about it ? You are 
not a swan mussel. Don’t interrupt. As I was saying—or 
about to say—these were very happy times, but they soon 
came to an end. However, I must not omit to mention that 
at this period we were termed Glochidiums , and so little did we 
resemble our parent that men* formerly thought us to be 
parasites. Well, time quickly passed, and one day we found 
ourselves ejected into the surrounding water, and now I found 
out what a weak, useless little creature I was, not even having 
power to swim, so that I soon found myself on the muddy 
* Rathke and Jacobson. 
