Echenets lunata. 413 
smaller, sub-ovate, light coloured, sometimes single, more commonly 
disposed in small imbricated patches over the large rhomboid scales, the 
whole of those upon any one of the latter scales seldom covering a larger 
space than would be equal to half its area. 
It may be presumed that Dr. Patrick Browne had never seen this spe- 
cies, from his character of ‘* pinnis posterioribus albo marginatis ;’’ 
which can scarcely apply to Ech. Naucrates, unless the specimen he had 
seen had had the original tinge of the margin of the fin obliterated by 
time or by being kept in spirits. Nor does he or any other authour cite 
Echeneis Remora as existing in these seas; yet I have a specimen of it 
which I myself took from the gills of a Xiphias, of which I shall per- 
haps say something by and bye. 
The same motives that lead me to send you my drawings of the small 
Cephalopterus, induce me to-inclose my figure of the above Echeneis.* 
But whatever satisfaction this fish, if it shall prove to bea non- 
descript, may from its novelty afford to Mr. Bennett, there is one organ 
common to the genus, from the investigation of which I cannot but be- 
lieve that he will derive yet greater pleasure. I allude to the structure 
and functions of the disk on the head, which have been hitherto very 
imperfectly noticed, although they well merit careful examination, and 
will afford a new illustration of the adaptation of means to ends with 
which the works of the Creator are so replete. It seems to me passing 
strange that an organ, which obviously performs so important an office 
in the ceconomy of the fishes of this genus, should have been so long 
ignored, and so generally slurred over by Naturalists with even Linnzus 
at their head; for surely his character of it, ‘‘ Caput supra planum 
** marginatum, transversé sulcato-serratum,”’ will be found to deserve no 
* This Echeneis is characterized in the “ Proceedings” of the Committee of 
Science and Correspondence of the Zoological Society, as the 
ECHENEIS LUNATA, Ech. corpore elongato, squamoso ; disci striis 22—25; 
pinnd caudali lunaté ; pectoralibus aoutis. 
D. 30 vel 32, A, 30 vel 33, C. 16, P. 21. V.6, 
Tas, XVIII. 
