148 



BULLETIN d?>, UNITED STATES NATIONAL MUSEUM. 



these tubes liaA'ing tninsverse septa about liali" way down, the lower 

 half being open. Inside of the parietes sharply ribbed to the sheath 

 (or in some old individuals, becoming nearly smooth above). 



Carinorostral diameter, 65 nnn. ; meight, 43 mm. (type). 



Greatest basal diameter, 47 mm.; height, G2 mm. (No. 48023). 



The type of this variety was taken by Dall at Unalaska (Cat. No. 

 9202, U.S.N.M.). It is on a very large valve of Placunanomia. 



It diii'ers from B. r. alasliemls by having septa in the upper part 

 of the parietal tubes only, as in B. r. apei-tus, which is a much thin- 

 ner, smaller, and generally rougher barnacle. There are 21 tubes in 

 the rostrum of this specimen. 



The mouth-parts of the largest specimen in group No. 38G70 

 (figured in my former paper, pi. 12, fig. 4), agi'ce Avith B. r. apc7^tus 

 No. 3S6G7. The third cirrus has no spinides, but there are some 

 minute fimbriated flat spines and slender sutural bristles as in B. 

 balanus. Some of the flat spines were seen on cirrus v, but none on 

 vi. The largest individual in this group of seven on the shell of a 

 Pecten measures 55 mm. high, 45 mm. in greatest diameter of the 

 base. 



Form suturalls (pi. 38, fig. 3). The Corwln took a peculiar form 

 in Alaska, exact locality not noted, in 1884. It is externally a good 

 deal like t^'pical B. rostratus^ as the shape is conic, with small orifice, 

 radii are sunken, parietes with angular edges. Otherwise it is more 

 like dalli. The wall is thick, with large square tubes, 17 in one 

 rostrum examined. Interseptal ribs, usually one or tAVo. The tubes 

 are open a long Avay up; no septa visible from beloAV. The labrum 

 (fig. He) has no teeth. The teeth of the mandibles are unusually 

 acute, but typical in arrangement (fig. -ild). Cirri and penis are 

 substantially as in B. r. ajjertus^ the posterior cirri having segments 

 Avith seven pairs of spines (fig. 41c). 



The type is Cat. No. 48025, U.S.N.M. 



I have some doubt whether this form Avill prove separable from 

 B. r. daJl'i Avhen large series are obtained. A specimen of dalli from 

 Kyska Harbor and one from Plover Bay have very narroAv radii, 

 but they are not sunken as in suturalis. 



