172 



BULLETIN" 93; UNITED STATES NATIONAL MUSEUM. 



the specimen figured having a basal diameter of 14 mm. The labrum 

 has a wide notch, with three teeth on each side ; only the upper one 

 marginal (fig. 54). 



In the elongated and club-shaped forms the radii become wide, 

 especially those of the rostrum. This is also the case in many 

 Atlantic specimens. Plate 41, figures 6 to 6e, are from Albatross 

 station 2851, near the Shumagin Islands, in 35 fathoms. The 

 scutum is long, its tergal margin decidedly longer than the basal 

 margin. The callus between the adductor pit and the articular 

 ridge is but slightly roughened, the interior being unusually smooth. 

 The articular ridge of the tergum is moderately recurved. On the 

 borders of the crowded colonies there are often transitions to the 

 normal conic form shown in figure 6(2. 



The labrum has two teeth on each side, larger than those of the 

 Greenland specimen figured. Maxilla with a very slight notch and 



Fig. 54. — B. crenatds. Union Bat, Bayne Sound. Top and lateral views x.5, axd tergum. 



seven subequal spines below the upper great pair, otherwise as in 

 the Greenland form. First cirrus has rami of 17 and 8 segments, 

 the posterior ramus half the length of the anterior. Second cirrus 

 with slightly unequal rami of 13 segments. Third cirrus with 15 

 and 13 segments, the posterior ramus two-thirds as long as the an- 

 terior. Sixth cirrus having segments with six pairs of spines and 

 sometimes a minute seventh pair. Penis exceedingly long, with an 

 acute point dorsally near its base, the end with a pencil of short 

 bristles. 



Similar but much smaller examples were taken by the U. S. R. S. 

 Corwin in the Arctic Ocean, on Ghrysodomus heros^ the contour 

 varying from conic and short to columnar. 



Southward on the Pacific coast we know little of the range of B. 

 crenatus^ as the smaller barnacles of California have been neglected 

 by collectors. At Point Richmond, San Franciso Bay, numerous 

 specimens were taken on TJmis plicata septentrlonalis (Reeve) by Mr. 



