302 BULLETIN 93, UNITED STATES NATIONAL MUSEUM. 



local races or " little species " like Balanus tintinnabulum or Tetra- 

 clita squamosci: My present study concerns American barnacles. I 

 have not taken the time to dissect, mount, and illustrate long series 

 of European individuals. Without such an investigation one would 

 not care to revise the master's conclusions. 



CHTHAMALUS STELLATUS STELLATUS (Poll). 



Plate 71, figs. l-4. 



This is equivalent to C. stellatus var. a, communis of Darwin, illus- 

 trated in his figures la, I/. 1 It is here figured from specimens from 

 the Bay of Naples, which I take to be the type locality. The broadly 

 oval or subcircular wall is conic, variable in height, often depressed. 

 It is corroded more or less extensively, but usually shows traces at 

 least of radiating ribs ; sutures moderately plain or obliterated ; radii 

 not developed; orifice rounded-oval. The color is an uneven, soiled 

 pale gray, usually showing black specks under a lens. Diameter 

 5 to 10 mm. 



The scutum is somewhat terra-cotta tinted within. The apex is a 

 right angle. Articular ridge strong, nearly straight, abruptly trun- 

 cate near the basitergal angle, above the deep articular furrow. 

 The pit for the adductor muscle is large and deep, those for the de- 

 pressor muscles generally distinct. No adductor ridge. 



The tergum is very broad above, narrow below. The upper mar- 

 gin is arched. Articular ridge is very broadty reflexed, triangular. 

 Articular furrow wide. No spur. The strong crests for the de- 

 pressor muscles barely crenulate the margin of the valve. The 

 external corrosion has carried away most of the original scutal mar- 

 gin, leaving the articular rib projecting. 



The palpi (fig. 84&) have very long spines in a straggling group 

 at the distal end, and a band of much smaller ones running down the 

 edge. 



Mandible nas four teeth, followed by a long, even series of very 

 small, crowded spines; the lower point terminating in one large, 

 stout spine, with two small spines below it. The third tooth is 

 bifid at the tip, the fourth more conspicuously so. There are long 

 bristles at the lower border (fig. S-M) . 



The maxilla has two large spines above, followed by three small 

 ones; the margin then advances and bears a group of moderately 

 strong spines, occupying the middle third of the edge. The lower 

 third has much smaller, slender, crowded spines. There are some 

 long spines on the basal border, and shorter ones on the upper border 



(fig. s-k>). 



Cirrus i has rami with seven and five densely hairy segments. 



1 As noted elsewhere, Darwin applied the name " var. communis " to the typical form 

 of every species having several varieties. 



