8 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 125 
In all likelihood the tetraclitids and chthamalids shared a common 
ancestry, but unlike the chthamalids the tetraclitids probably evolved 
and deployed far more rapidly. The balanids, on the other hand, 
probably evolved from the chthamalid lineage, but at a much later 
time. Unfortunately, the fossil evidence documenting these evolu- 
tionary steps remains to be discovered. 
Inclusion of the tetraclitids in the Balanidae would clearly appear 
to be precluded on the basis of the foregoing. By the same token 
their inclusion in the Chthamalidae would serve only to weaken the 
definition of this group also. Because no intergrades or transitionary 
forms are known to occur between the Balanidae and tetraclitids, 
separation of these two groups at the familial level is clearly warranted. 
Genus Tetraclita Schumacher, 1817 
Tetraclita (Tetraclita) stalactifera (Lamarck) 
FIGURE 2 
Balanus ponderosus [Lightfoot, 1786,] p. 89.—Dillwyn, 1825, p. 23. 
Balanus stalactiferus Lamarck, 1818, p. 894.—-Lamy and André, 1932, p. 222. 
Balanus latus Lamarck, 1818, p. 397.—Lamy and André, 1932, p. 222. 
C[lonia] stalactifera.—Chenu, 1843, pl. 4, figs. 6-8. 
Tetraclita porosa var. communis Darwin, 1854, in part, p. 329, pl. 10, fig. la, li 
(?), 1k (?). 
Tetraclita porosa.—Verrill, 1901, p. 22.—Bigelow, 1901, p. 180. 
Tetraclita squamosa stalactifera.—FPilsbry, 1916, p. 254, pl. 59, figs. 1, la, 1b.— 
Oliveira, 1940a, p. 138; 1941, p. 7, pl. 1, figs. 1, 2, pl. 2 (fig. 4), pl. 10 (figs. 1, 
3, 6); 1947, p. 715.—Stephensen and Stephensen, 1950, p. 388; 1952, p. 8.— 
Henry, 1954, p. 444; 1958, p. 224, pl. 1, fig. b, pl. 5, figs. a, b.—Newell, 
Imbrie, Purdy, and Thurber, 1959, p. 209.—Voss and Voss, 1960, p. 102, 
106.— Ross, 1962, p. 31.—Rehder, 1967, p. 16. 
Tetraclita stalactifera.—Pilsbry, 1927, p. 38. 
Tetraclita porosa stalactifera—Nilsson-Cantell, 1933, p. 508; 1939, p. 5. 
Tetracliia squamosa.—Smith, Williams, and Davis, 1950, p. 184.—Marshall, 1953, 
p. 435.—Werner, 1967, p. 70.—Multer and Milliman, 1967, p. 260, fig. 2. 
MarTERIAL.—Scotts Head Bay, at southern end of Soufriere Bay, 
approximately 15°12’40” N, 61°22’40” W; 0.5 meters; May 17-28, 1966; 
about 150 specimens. Middle Bay, adjacent to town of Marigot, 
approximately 15°32’21” N, 61°17’28” W; intertidal, on basaltic rocks; 
April 15-30, 1966; 4 specimens; same locality as that cited by Kirsteuer 
(1967). Western end of Panto Hole Bay, approximately 15°32’21" N, 
61°17/31" W; intertidal, on basaltic rocks; May 1-10, 1966; about 
125 specimens. 
Dracnosis.—Sheath of shell tinted plumbeous black and opercular 
plates violet black or raisin black with whitish or paler borders and 
ridges. Parietes relatively thin; tubes large, commonly in 3-5 rows. 
Radii very poorly developed or obsolete. Labrum with slight notch 
