THE SESSILE BARNACLES. 157 



scuta are faintly pink tinted. Others from 7 and 45 fathoms have 

 the usual ribs. All are rather small. 



A lot taken by Mr. O. Bryant 20 miles south of Nain, Labrador, 

 have the terga hardly beaked, and white. The longitudinal striation 

 of the scutum is very faint. They are small, measuring 8 mm. in 

 diameter. 



Specimens externally similar to typical B. halanus, but frequently 

 larger, are common on the American coast, and on Georges Bank 

 (pi. 35, figs. 2, 2c/.) A usually larger form from Bar Harbor, Maine 

 (pi. 34, ligs. 1, la, 6), has six ribs on the rostrum, four and five on 

 the latera. Others imxj have as many as eight ribs on the rostrum. 

 The ribs are not nearly so strong as in the form called B. genlcuJatus 

 by Conrad. The individual figured has the posterior ramus of the 

 first cirrus two-thirds as long as the anterior, segments 25 and 13 

 (fig. 13^). Rami of second cirrus somewhat unequal, of 18 and 11 

 segments. The anterior ramus of cirrus iii has a few spinules, most 

 numerous about the tenth segment (p. 152, fig. 43c). There are also 

 some delicate spines near the distal sutures of the segments. Most 

 of the segments of this cirrus have no spinules. Cirrus iv has a few 

 spinules on some of the median segments (p. 152, fig. 43c, sixteenth 

 segment of anterior ramus). The sixth cirrus has 50 segments bear- 

 ing four or five pairs of spines (p. 152, fig. 43/), agreeing thus with 

 British B. hdlaniis. Thelabruin (p. 152, fig. 43c?) has no teeth, therel)y 

 agreeing with some West American forms. Penis (p. 152, fig. 437i) 

 has a basidorsal point. In some lots from the banks, on Pecten 

 islandimis, Albatross stations 2079 and 2080, the diameter does not 

 exceed 16 or 20 mm. ; ribs not very strong. The walls are thin, very 

 elaborately denticulate around the parietal tubes at the base (pi. 35, 

 figs. 2,2«)._ 



An individual from Portland, Mame (pi. 34, fig. 2; pi. 35, fig. G), 

 collected by J. W. Mighels (Cat. No. 48016, U.S.N.M.) illustrates the 

 mutations sometimes encountered in Balanus. The rostrum and lat- 

 eral compartments are many-ribbed and symmetrically spreading. 

 Their bases rested upon the shell of Pecten magellanicus. The carina 

 and carinolateral compartments rested upon some irregular object 

 on the Pecten, and have the vertical, rugose, obsoletely ribbed walls 

 of the ordinary cylindric form of B. halanus. The basal edges of 

 the spreading compartments are remarkably wide between the inner 

 and outer plates of the wall, and the incomplete septa springing 

 from the outer plate are very long, almost reaching to the inner 

 plate. This peculiarity I have seen elscAvhere only in one individual 

 from Cork. The lateral diameter of the base is 59 mm. 



Plate 34, figure 4, growing on a smooth pebble, and figure 5, on 

 Pecten magellanictts, further illustrate the forms of the fishing banks. 



