THE SESSILE BARNACLES. 



109 



flat, opposed sutural edges, which have fine, irregular, denticulate 

 crenulation. The alse are narrow, with very oblique summits. The 

 rostrum is short and broad ; lateral compartments very broad ; carino- 

 laterals very narrow. There are deep, rather roomy hollows behind 

 the lower edge of the sheath. 



The interior surface is rather strongly ribbed near the base, becom- 

 ing smooth above. Each rib is continuous with a septum in the wall, 

 as usual. The parietal pores are large, square, separated by thin 

 septa, which at their junction with the inner plate of the wall are 

 thicker and denticulated, as usual. There are a few small, incomplete 

 septa arising from the outer plate of the wall. The parietal pores 

 are not filled up in the upper part, but transverse septa are rather 

 numerous, from the base up. 



The basis is strong, flat, rather well provided with round pores, 

 but there is no underlying cellular layer. It clings very firmly to 

 the walls. 



This large and handsome barnacle is known by two individuals 

 calcified together, which grew on some nearly flat object. The 

 opercular plates and body were not collected. It is remarkable for 

 the absence of radii, which are represented only by irregularly rough- 

 ened white thickenings along the carinad borders of the lateral com- 

 partments; also for the intimate union of the carina and carino- 

 lateral compartments, the sutures being merely linear or wholly 

 obliterated, although the surface is not eroded. The color and the 

 very short rostrum (if the latter is not the result of some unusual 

 situation or position of the individuals), are also notable. The 

 species should be readily recognizable, since there is no west coast 

 barnacle which could be confused with it, to my knowledge. 



The affinities of this form can not be worked out until complete 

 specimens come to hand, but the walls suggest relationship with B. 

 concavus and possibly B. nubilis; at all events, it belongs to the 

 same division of the genus, group C of Darwin's classification. The 

 transverse septa of the parietal tubes serve to further distinguish B. 

 regalis from both B. nubilis and B. concavus pacificus. Among the 

 forms of B. concavus, it has some superficial resemblance to B. c. 

 proteus, of the Virginian Miocene. It should be noted also that there 

 is a rare ribbed form of B. c. pacificus, shown in plate 23, figure 2c. 



As this is one of the largest and handsomest west coast barnacles, 

 it is hoped that living specimens will be looked for, in order to com- 

 plete its description. 



