142 



BULLETIN 93^ UNITED STATES NATIONAL MUSEUM. 



of the other ramus. A general view of the cirri of one side is given 

 on page 8, figure 6. The spines do not show in the photograph. 

 The cirri are pigmented, so that spinules are hard to see. There are 

 subsutural multilld spinules on cirri iv and v, and numerous simple 

 spinules on the segments of cirrus iv. 



A rather thin, smooth specimen (Cat. No. 4802G, U.S.N.M.), which 

 had grown on a large Mytiliu^^ was taken at Cape Douglas, Alaska, 

 by T. W. Stanton during the Shelikof Strait exploration in 1904. 

 The radii are but slightly sunken and rather narrow. The interior 

 is very closely and sharply ribbed up to the sheath. The rostrum has 

 part of the tubes subdivided, so that there are 45 parietal tubes, an 

 extraoi'dinary number. This is evidently correlated with the thin- 

 ness of the wall, bringing the inner and outer laminte close together, 

 so that the lamellae, which form imperfect septa in ordinary rostratus. 

 become concrescent, forming complete septa. The transverse septa 

 occur nearly to the basal edge (pi. 38, fig. 5). Opercular valves 

 wanting. 



All of the localities for this subspecies are along the Aleutian 

 chain and the southern coast of the Alaskan Peninsula. 



BALANUS ROSTRATUS HETEROPUS, new subspecies. 



Plate 36, figs. 7, la, 8. 



Type.— Cut. No. 48022 U.S.N.M., from Albatross Station 2864, 

 latitude 48° 22' north, longitude 122° 51' west; Puget Sound, Wash- 

 ington, in 48 fathoms; bottom temperature, 47°.7 F. 



Other localities. — San Juan Islands, Puget Sound, between 10 and 

 50 fathoms ; Homer Wheeler, in collection of the Academy of Natural 

 Sciences of Philadelphia. 



The barnacle resembles B. r. apertus, being steep-walled, with large 

 orifice. It is rather thin, the parietes smoothish, not ribbed or spi- 

 nose; radii wide, only slightly sunken, with level summits when un- 

 broken. The parietal tubes are small (18 to over 30 in the rostrum), 

 with many transverse septa, w^hich extend nearly to the base. 



Greatest carinorostral diameter, 18 mm. ; height, 20 mm. 



Greatest carinorostral diameter, 17 mm.; height (of rostrum, the 

 longest compartment), 27 mm. 



The scutum has longitudinal striae in the intervals between the 

 growth-ridges, but they do not crenulate the latter. The adductor 

 ridge is rather strong in some individuals, very weak in others. 



