704 
EDWAKD W. SHANiN. 
interesting, but lias opened np a wider scope of research than 
I had anticipated. 
On consulting various books on fishes I found that the 
lobe was invariably figured in the best drawings of the 
salmon ; in Day’s ^ British Fishes/ for instance, it can clearly 
be seen.^ At the same time no reference to the occurrence of 
such a lobe could be found in any book which might be 
expected to throw light upon a structure of this nature. I 
made a dissection of the adipose lobe, and so found that it 
was supported at its base by a splint of bone ; the posterior, 
or distal, extremity of this bone was united to, but not 
fused with, the outermost fin-ray. This splint of bone is 
depicted in a figure of the pelvic fin skeleton of the trout in 
Parker and Haswell’s 'Text-book of Zoology,’" and it is 
there mentioned that " the adipose lobe of the pelvic fin is 
supported by a small scale-like bone.” By treatment of 
sections of the lobe Avith osmic acid and witli Sudan III, I 
was able to satisfy myself that a considerable amount of fat 
was pi-esent in the lobe ; I further observed from my sections 
that the lobe was stiffened by a plate of hyaline substance 
Avhich ran throughout its length. I was fortunate enough to 
obtain a series of young salmon ranging in age from one to 
five months ; from these I prepai’ed serial sections of the pelvic 
region, and was thereby enabled to observe the origin and 
groAvth of the adipose lobe. From these observations I have 
been able to demonstrate that this so-called "adipose lobe” 
is nothing more or less than an enlarged scale Avhich has never 
pierced its connective-tissue pocket. That a scale is capable 
of becoming a fin-like structure is an additional support to 
Mr. Goodrich’s hypothesis, namely, that the dermal fin-rays 
(lepidotrichia) are modified body-scales, if his lucid argument 
has not already gained general acceptance, 
I further examined the condition of the pelvic fins of other 
Teleosteans; and my observations from illustrations and from 
actual specimens go to show that an enlarged scale in the 
' See also fig. 1 herein. 
- Ed. 2, vol. ii, fig. 864. 
