356 T. H. Withers — The Cirripede Brachi/lepas cretacea. 



From a study of the new material from Liineburg. including the 

 scuta, terga, and upper latera, it is evident that the capitulum must 

 have been built up in the manner suggested by Dr. Woodward. The 

 upper latera, liowever, are rather different, being somewhat larger 

 and narrower than is indicated by the liypothetical figure in his 

 restoration ; they closely resemble the homologous valves of P. fallax 

 and of the recent P. mitella (see Text-fig. 2). 



We have now certain knowledge of the whole of the valves that 

 formed the capitulum of B. Naissanti (see restoration, Text-fig. 4), 

 and a comparison of the isolated valves with those of the recent 

 P. mitella shows how extraordinarily alike the upper whorl of 

 valves is in its structure and arrangement. It is especially noticeable 

 that the upper latera are of the same type. In B. Naissanti the lines 

 of growth on the inner surfaces of the cai'ina and rostrum show that 

 the upper part of these valves must have projected freely, the rostrum 

 to a greater extent proportionally than the carina. The scuta and 

 terga undoubtedly articulated together, and the greater portion of the 

 upper latera must have overlapped the scuta and terga, since only 

 a small triangular portion of its base appears to have been covered 

 by the membrane (corium) lining the inside of the valves of the 

 capitulum. In fact, the upper and main whorl of valves had pi'ecisely 

 the same method of arrangement as in P. mitella. As one would 

 naturally expect, the valves of B. Naissanti differ somewhat in shape 

 from those of P. mitella, the most important differences being that 

 the rostrum and carina are more squat and semicircular, approaching 

 in this respect the sessile forms of Cirripedes, although they do not 

 possess radii or alse; the scuta differ mainly in having a straight 

 basal margin. In the case of P. mitella (see Text-tig. 2) it will be seen 

 that there is only one whorl of valves below the rostrum, including 

 a sub-carina and sub-rostrum, whereas in B. Naissanti (see Text-fig. -i) 

 there are at least four whorls of imbricating plates, with no suh-carina 

 or sub-rostrum, an arrangement that reminds one of the base of the 

 capitulum in the sessile Cirripede Catopliragmus (see Text-fig. 3), in 

 which old individuals have as many as ten or even more whorls of 

 valves. The most important character of B. Naissanti and one of great 

 significance, although it does not appear to have been described 

 previously, is that the two and possibly three outermost whorls of 

 imbricating valves have a basal ledge which projects inwards and is 

 fixed by its somewhat acute inner extremity into a median notch at 

 the base of the valve immediately in front of it. The valves of the 

 innermost whorl have no such basal ledge, but have a median notch at 

 the base, by which they are fixed externally to the projecting ledge 

 of the surrounding whorl of valves. These basal ledges lie almost on 

 the same plane, together forming a shelf or platform extending round 

 the base of the capitulum. The formation of this platform seems to 

 preclude the possibility of B. Naissanti having had a peduncle, and 

 the probability is that it had a membranous basis and that the outer 

 whorls of valves were in close proximity to the surface of attachment, 

 as are the outer whorls of valves in the recent Catophragmtispolymerus. 

 Firm attachment for the membranous basis may have been afforded by 

 the edges of the laminae which stand out as sharp ridges on the lower 



