196 



BULLETIN 08, UNITED STATES NATIONAL MUSEUM. 



the posterior ramus over three-fourths the length of the anterior. 

 Cirrus ii has slightly unequal rami of 9 segments. Posterior cirri 

 with three pairs of spines on the segments. By the proportions of the 

 rami of the first cirrus, this form differs strongly from B. h. nip- 

 poiwnsis (station 5003), but otherwise is much like it. 



Several other lots are labeled Alaska, without nearer indication of 

 locality. 



BALANUS HESPERIUS form L^VIDOMUS, new form. 

 Plate 50, figs, l-l/; 2-26. 



Type. Cat. N"o. 2106, Acad. Nat. Sci. Phila., from San Juan 

 Islands, Puget Soimd, collected by Homer Wheeler. 



Distribution. Monterey, California, to Alaska. 



The shape varies from broadly conic to shortly cylindric. The 

 external walls are smooth in the typical form of the subspecies; the 

 ribs on the inner faces of the parietes are regular. The scutum has 

 feAver, more widely spaced growth-ridges than in Jiesperius ; they are 

 often low, or very weak. The basal margin of the scutum is usually 

 longer. 



I segregate this form with some hesitation, yet after going over 

 the material repeatedly there seems to be a constant difference in the 

 external sculpture of the scuta, which it would be a fault to ignore. 



As the geographic ranges of the two forms overlap in the north 

 and there are some transitional specimens, I do not call it a sub- 

 species. 



