206 BALANIDJE. 



spur, forms a nearly straight line, but with the portion on the carinal 

 side very slightly hollowed out. Crests for the depressor muscle are 

 well developed. 



Compartments. — The radii and alee always have their summits 

 oblique : the sutural edges of the radii are deeply penetrated by pores 

 between the strongly denticulated septa : the sutural edges of the ala? 

 are quite smooth : the tubes in the parietes are crossed in the upper 

 part of the shell by septa. Basis tubular, with an underlying can- 

 cellated mass. 



Mouth. — Labrum with the teeth either absent or very small : man- 

 dibles with the fourth and fifth teeth rudimentary : maxillae with a 

 small notch under the two upper spines ; near the lower angle, two 

 spines, one beneath the other, are larger even than the upper pair ; 

 beneath the lower pair, there is a tuft of fine spines. Cirri, segments 

 protuberant in one ramus of the first cirrus and in both rami of the 

 second cirrus ; posterior cirri with the segments short and broad, each 

 bearing three pairs of spines, with a small intermediate tuft. 



Affinities. — This species in all essential respects comes very near to 

 the three last varieties of B. tiatinnabulum, which have the orifices of 

 their shells toothed. The smoothness of the scutum, with its per- 

 sistent epidermis, — its peculiar shape, — its small and not reflexed 

 articular ridge, — together with the crests on the tergum for the de- 

 pressor muscles, are sufficient diagnostic characters. Even in general 

 habit and tint of colour, this species has a different aspect from B. tin- 

 tinnahulum. In some respects B. tidipiformis leads into the species 

 included in the third section of the genus. 



3. Balanus psittacus. PI. 2, fig. 3 a — 3d. 



Lepas psittacus. Molina. Hist. Nat. Chile (1788), vol. i, p. 223. 

 Balanus picos. Lesson. Zoolog. Voyage de la Coquille (1S29). 



— TINTINNABULUM (var. c.) Ra?izani. Mem. di Storia Nat. 



tab. 3, fig. 1—3 (1S20). 



— cylindraceus. Lamarck, in Chenu. Illust. Conch. Tab. I, 



fig. 17, Tab. 5, fig. 7, scd non var. (c.) in Lamarck, 

 Animaux sans Vert., (1818). 



— psittacus. King and Broderip. Zoolog. Zournal, vol. v 



(1832-1834), p. 332. 



Shell, pale dirty joink ; orifice hexagonal. Scutum with 

 the articular ridge very small, confluent with the very promi- 

 nent adductor ridge ', forming a tubular cavity, which extends 

 up to the apex of the valve. Tergum with the apex pro- 

 duced, needle-// \ke t purple : spur placed at less than its own 

 widtli from the h asi -scut al angle. 



