OTJON. 



Leach. Supplement to Eneycl. Brit. 



CORPUS pedunculatum, tunica membranacea 

 abrupte ventricosa supern^ obtectum; antice 

 apertura hiante. Tubi duo, subcylindrici, re- 

 trorsum versi, truncati, extremitate pervii, ad 

 apicem tunicse. Valvse testacese quinque, sepa- 

 ratae, duae semilunatag ad latera aperturse, 

 unica minutissima dorsalis, caeterae pariter mi- 

 nutissimae, terminales. 



The Lepas aurita, Linn, may be considered as the type of 

 this most singular Genus, which is distinguishable from 

 Cinaras, not only by its tubular corniform terminal pro- 

 cesses, but by its being almost destitute of the dorsal and 

 terminal shelly valves ; indeed these are so minute that 

 Lamarck has overlooked them, and described it as quite 

 destitute of them; but Leach has not failed to observe 

 and mention them^in his account of the Cirripedes in the 

 Supplement to Encyclopedia Britannica." 



The Otion is a pedunculate body covered with a 

 membranaceous skin, of which the upper part is abruptly 

 ventricose, and has an aperture for the passage of the 

 numerous fringed arms, or tentacula, placed in front just 

 below the summit. Two irregularly cylindrical, truncated, 

 open, reflected tubes, are conspicuous on the upper pos- 

 terior extremity; these appear to be very variable in size 

 in the different species, but they are always a very remark- 

 able character. There are five small testaceous valves, > 

 all widely separated from each other; two of them which 



