THE SESSILE BARNACLES. 



169 



The first cirrus in a specimen from Inglefield Gulf (pi. 40, figs. 4, 

 Cat. No. 24911, U.S.N.M.), has rami of 15 and 10 segments. 

 Cirrus ii has 12 and 10 segments, the anterior longer by 3 or 4. Cirrus 

 iii has 15 and 16 segments, the anterior ramus one-quarter longer 

 than the inner. Both rami have areas of short spinules on the 

 anterior part of the segments, and others along the posterior borders. 

 The latter are more developed than in specimens from any other 

 locality examined. Cirrus iv has a few minute spinules near the 

 anterior margins of some segments of the outer ramus and some 

 erect spinules near the posterior margin (fig. 50). 



Sixth cirrus with segments bearing five pairs of spines, and usually 

 some minute ones at the bases of the two larger pairs. The spines 



Fir;. 52. BALANUS CRENATUS. a, T> } SCUTUM AND TERGUM OF A GREENLAND SPECIMEN, CAT. 



NO. 24911. C, TERGUM OF A SPECIMEN FROM THE GRAND BANK, ALBATROSS STATION' 

 2462, WALL SIMILAR TO PLATE 40, FIGURE 6. 



at the posterior distal angles are about as long as the segments. 

 Penis is longer than the posterior cirri. 



The maxilla (fig. 49&) has no notch under the superior pair of 

 large spines; below them there are nine subequal spines, with two 

 brushes of bristles at and below the rounded lower angle. The 

 labrum (fig. 49) has two exceedingly small teeth on each side. 



The form from the Grand Banks of Newfoundland (pi. 40, fig. 1) 

 is characteristic. The walls taper but little upward, leaving a large 

 orifice, which is deeply toothed in the young, but in old specimens 

 the points are often broken or worn oft'. The parietes have massive, 

 irregular, rounded ribs. There are generally three or four ribs on 

 rostrum and lateral compartments, one on the carinolateral, two to 

 four on the carina, in the half -grown stage (pi. 40, fig. G, Cat. No. 

 9215) ; but in old ones the number is increased by division of the ribs. 

 The tergum is broader than in English crenatus, with its carinal 

 margin longer. It is broader than the scutum. Often the spur is 

 shorter than in Greenland crenatus. There are also columnar (pi. 

 40, fig. 2) and tubular forms, flaring toward the orifice (pi. 40, figs. 

 5-5&), quite like those from Greenland. Two specimens of the col- 

 umnar form out of the lot from Albatross station 2462, Grand Banks, 



