TETRACLJTA PURPURASCENS. 337 



4. Tetraclita PURPURASCENS. PL 11, fig. 1 a — 1 d. 



Lepas purpurascens.* Wood'' s General Conchology, p. 55, PI. 9, 



fig. 42, 1815. 

 Balanus plicatus. Lamarck. Animaux sans Vertebres, 1818. 

 — — et puncturatus. Chenu. Illust. Conch., Tab. 4, 



fig. 3 et 12. 

 Conia depressa (!) <7. E. Gray. Appendix, Dieffenbach's Travels 



in New Zealand, 1843 (sine descript. vel 

 figura). 



Shell depressed, pale purple or dirty white, with the sur- 

 face longitudinally ribbed, or corroded and granulated ': 

 radii or even sutures none, or radii well developed and 

 broad, with their summits parallel to the basis : basis mem- 

 branous : scutum transversely elongated : tergum small, with 

 the spur extremely short and rounded. 



Hab.— Sydney, New South Wales; "Flinder's Lagoon, Sir C. Hardy's Island, 

 Barrier Reef; Xing George's Sound, Western Australia; A r an Diemen's Laud; 

 New Zealand, adhering to Pollicipes spinosus ; Mus. Brit., Cuming, Stutchbury, 

 Darwin, &c. China (?) attached to Pollicipes mitella, Mus. Brit, and Stutch- 

 bury. Generally attached to tidal rocks, sometimes to shells. Very 

 common. 



General Appearance. — Shell generally much depressed, in a few 

 cases rather steeply conical, in one single instance cylindrical, but not 

 much elongated. Colour, when alive, pale, but fine purple; I presume, 

 judging from some dryed specimens, sometimes dirty white. The state of 

 the surface varies remarkably : about halt' the specimens (fig. \a) which I 

 have seen, had the outer lamina of shell quite removed, and the surface 

 granulated, owing to the projecting andexposedtipsof theupfilled parietal 

 tubes ; the radii are not developed, and often even there is no trace of the 

 four sutures; the rather large orifice is somewhat rounded, and the two 

 scuta, with their surfaces disintegrated, have their middle parts deeply 

 indenting the terga. The shell, in the oilier and perhaps more common 

 condition (fig. 1 b), has the outer lamina preserved, and is longitudinally 

 ribbed with generally at least five or six ribs on each compartment : 

 the radii are here very wide, and extend from tip to tip of the compart- 

 ments, so that their summits are parallel to the basis ; they are gene- 



* The descriptions given by Wood and Lamarck are fuller and more accurate 

 than is usual in the case of Cirripedes, and I have no doubt regarding these 

 two names. The Conia depressa of Dr. J. E. Gray is, as I know from having 

 seen the original specimens, the young of this same species; the name is unac- 

 companied by any description or figure. 



A/A 



