238 BALANIDJ3. 



menclature of the present species, I have little doubt that I 

 have properly identified the Italian fossil specimens with 

 B. concanis of Bronn, who has given a very good figure of 

 this species in his ' Lethaea Geognostica;' it must, however, 

 be confessed that the longitudinal striae on the scuta are not 

 there represented. Considering the large size and frequency 

 of this species in Europe and in the United States, it has 

 probably received several other names, besides the two in- 

 correct synonyms, quoted at the head of this description. 

 I should add that the true B. cylindraceus (not var. c) of 

 Lamarck, according to the plate given by Chenu in his 

 ' lllust. Conch.,' is the B. psittacus of South America. I 

 have seen in collections specimens of B. concavus labelled as 

 B. tidipa of Poli (B. tulipiformis of this work), — a very 

 natural mistake, without the opercular valves be carefully 

 examined. 



General Appearance. — Shell conical, often steeply conical ; orifice 

 rather small, with the radii narrow, and generally in the fossil speci- 

 mens very oblique ; surface generally smooth, sometimes rugged, and 

 in the coralline crag specimens generally ribbed longitudinally, the 

 ribs being narrow. Colour various, either dull reddish-purple with 

 narrow nearly white, or wider dark longitudinal bands; or, again, 

 pale rosy-pink with broad white bands; or lastly, wholly white. The 

 radii are either darker or paler than the parietes. The opercular 

 valves are either dark purple or nearly white. Pale pink and white 

 stripes are visible on some of the Italian and Portuguese tertiary spe- 

 cimens ; and in most of the fossils the sheath is tinged dull red. 



Dimensions. — The largest actually recent specimen which I have 

 seen, from the Philippine Archipelago, had a basal diameter of 1*2 of 

 an inch; the Peruvian pleistocene specimen is 1*7 in diameter; speci- 

 mens from the crag and from the Italian deposits, however, sometimes 

 slightly exceed two inches in basal diameter, and three in height. 



Scuta : these in young and moderately-sized specimens are striated, 

 sometimes very faintly, but generally plainly, causing the lines of 

 growth to be beaded ; but often, in large and half-grown specimens, 

 the lines of growth are extremely prominent, and being intersected by 

 the radiating striae, are converted into little teeth. As the striae often 

 run in pairs, the little teeth frequently stand in pairs, or broader teeth 

 have a little notch on their summits, bearing a minute tuft of spines. In 

 very old and large specimens, the prominent lines of growth are generally 

 simply intersected by deep and narrow radiating striae. In one case, 

 a single zone of growth in one valve was quite smooth, whilst the zones 

 above and below r were denticulated. The valve varies in thickness, 

 which I think influences the prominence of the lines of growth and the 

 depth of the striae. These striae often affect the internal surface of the 

 basal margin, making it bluntly toothed. The articular ridge is rather 



