174 Professor MacGillivray on the Cirripedia, 



subovate appendages, communicating below with the interior of the 

 tegmen. Peduncle cylindrical, fleshy, constricted at the top, its epider- 

 mic coat continuous, with the dermal lining of the tegmen, on the inner 

 surface of which is the slight layer of pigment, continuous or inter- 

 rupted. 



This genus, instituted by Dr Leach, but by some united with 

 CJineras, under the common name of Gymnolopas, is composed o£ 

 very singular-looking animals, which are found adherent to ships' 

 bottoms, floathig timber, and many other objects. It is very nearly 

 allied to Cineras, and the species of the two genera are usually found 

 intermixed, and even affixed to each other. 



It differs from Cineras in having the two bursiform appendages 

 at the top, and in other particulars ; from Lepas in having more 

 branchial filaments, the cirri much shorter, the tegmen almost en- 

 tirely coriaceous ; but still it is closely allied to it, and has the same 

 calcareous pieces, although greatly reduced in size. 



These Cirripedia are found in great profusion on vessels that 

 have been on long voyages, as well as on turtles, fishes, and other 

 objects. 



Of this genus only one species has occurred. 



1. Otion aurilHs. Common Eared Barnacle. 



Tegmen cuculliform, cylindraceo-globose, depressed, brown ; appen- 

 dages ovate, puckered, dark-brown ; marginal plates oblong, geniculato- 

 angulate, twisted, thick, broader and abrupt above, tapering and obtuse 

 below ; upper plates linear ; dorsal very minute, oblong, convex ; pe- 

 duncle brown, glistening with bluish-gray, paler at tlie base. 



The body subovate, little compressed, incurvate, very convex on the 

 back, moderately narrowed behind; anteriorly soft and prolonged, with 

 a very thin membranous white or greyish integument, which becomes 

 firmer on the hind part. The mouth forming a large prominence, and 

 having a vaulted, bullate, rounded lip, with two external adnate thick 

 palpi, free at the end, curved forwards and inwards, with an incurved 

 spinosc tip, and three pairs of incurvate, compressed, maxillar appen- 

 dages, lanielliform at the end. The first or outer pair with the terminal 

 lamina subtriangular, pointed, with six external, marginal, acuminate 

 teeth, of which the posterior is very large, and the anterior very minute ; 

 the second, with the lamina subovate, with five short, convex, ciliated 

 lobes ; the third or inner, narrower and ciliate. 



The first pair of feet shorter than the rest, immediately above or be- 

 hind the mouth ; the second pair at some distance, the rest close to- 

 gether ; the first pair subcylindrical, compressed, obliquely grooved on 

 the back, with four joints; their cirri short, broad, tapering, with thir- 

 teen joints ; the other feet compressed, obliquely and deeply grooved 

 on the back, with two joints, and longer, compressed, tapering cirri, the 

 last having seventeen joints ; all the cirri lobed and ciliate on the edge 

 next the mouth, the bristles generally ten or twelve on each lobe, in two 

 series ; the dorsal bristles very small and adpressed. 



The first foot has a long, cylindrical, tapei-ing, branchial filament from 

 its last joint externally, another having a rounded prominence at its base 

 from the next joint, a third very short from the basal part, and not far 

 from it, OQ the side of the body, a beaiispherical knob. The next four 



