FEMALE. 185 



a high power, a folded structure, and is penetrated by a few 

 tubuli, whereas the harder blue portion has a cellular or 

 scaled appearance. The spines of the peduncle exhibit, 

 in a smaller degree, similar phenomena. 



Peduncle. — This, as already remarked, cannot be 

 distinctly separated from the capitulum ; it is much 

 compressed ; it is composed of unusually thin and deli- 

 cate membrane, transversely wrinkled and thickly clothed 

 with long cylindrical horns or spines of chitine. These 

 horns (fig. 8 c) are not the analogues of the spines which 

 are articulated on the external membranes of many 

 Pedunculated and Sessile Cirripedes, but of the calcified 

 scales on the peduncle of Scalpellum and Pollicipes ; for 

 they pass through the membrane (the underlying corium 

 being marked by their bases) and are persistent, being 

 added to, like the valves, during each successive period 

 of growth. Their bases are concave, so that a section of 

 the layers of growth exhibits a series of pointed cones, 

 one within another. Each spine is nearly cylindrical, 

 irregularly curled, and nodose or slightly enlarged at 

 intervals : the apex smooth and pointed ; the exterior 

 surface longitudinally and finely ribbed, like the valves. 

 The spines increase irregularly in size from the bottom 

 to the top of the peduncle, those at the carinal and rostral 

 ends being generally the longest ; they point upwards and 

 hide the bases of the valves. They are not arranged sym- 

 metrically, and new ones are formed over all parts of the 

 peduncle. They are formed of the same substance as 

 the valves, and do not contain any calcareous matter. 

 These horns are yellowish, generally ringed with pale and 

 dark blueish brown, which on pressure becomes slightly 

 opalescent with pale blue and fiery red : sometimes only 

 the upper horns are thus ringed, and in rare instances all 

 are simply yellowish. The muscles of the peduncle run 

 up to the bases of the four valves. 



Surface of Attachment. — The cement appears to pro- 

 ceed from only two points. In some specimens, a con- 

 siderable length of one side of the peduncle was fastened 



