J'j(./ieHcis lunula. ll*^ 



smaller, sub-ovalo, li<^lit colonrcfi, somf-tiinos sirr^Ic, moro commonly 

 disposed in Hinall im'jricatod [>atf;h<;H over thr; larg<; rhomboifl sc-alcs, tlie 

 whole of thrwe upon any one of thr; latter scales seldom covering a larger 

 spacf than would he ef|ijal to half its area. 



It may he [jresuined that Dr. Patrick llrowne had n»;ver seen thi« spe- 

 cies, from liis character of " (jinnis posteriorihus alho rnarginatis ;" 

 which can scarcely a[)ply to Ech, Naucralcs, urdess th(; sjieeim<;ri he had 

 seen had had the orij^inal tinge of the margin of the fin ohliteraled hy 

 time or hy being kept in spirits. Nor does he or any other uuthour cite 

 EcJifinc'iH JOirnora as existing in these seas; yel I have a specimen of it 

 which I myself took from the gills of a Xipldai, of which I shall per- 

 ha[>8 say something by and bye. 



The same motivf^ that lead me to send you my drawings of the small 

 Ccphuloptcrua, induce me to inclwe my hgure of the above Echcncu.* 



But whatever satisfaction this fish, if it shall prove to be a non- 

 descript, may from its novelty afford to Mr. I'ennett, there is one organ 

 common to the genus, from the investigation of whidi I cannot but be- 

 lieve that he will derive yet greater pleJisure. I allude to the struciure 

 and functions of the disk on the head, which have been hithert^> 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 Oiconomy of the fishes of this genus, should have fjeen Sf> long 

 ignored, and so generally slurred over by Naturalists with even Linnaeus 

 at their head ; for siirely his character of it, "Caput supra planum 

 " marginatum, transvers*^ sulcato-serratum," will be found to deserve no 



• ThiK Echenvin i% f;haractcri7,cd in the " Proceed iugn" of the Committee of 

 Scieacc and Correspruidence of the Zoological Society, an the 



EcHENKrs r.r/NATA J-Uh. corpora c.lon^alo, nquamoifi ; diici »triia 22 — 2.0; 

 pinnd caudnli lunat/i ; jicclnrnlihuii aoutii. 



D. 30 vol 32. A.30vel33. C. 16. T. 21. V. 6. 



Ta»<. XVIII. 



