HETERALEPAS CORNUTA (DARWIN) IN THE EASTERN PACIFIC ABYSSAL FAUNA (CIRRIPEDIA THORACICA) BY ARNOLD ROSS Natural History Museum, P.O. Box 1390, San Diego, California 92112, U.S.A. The lepadomorph barnacle Heteralepas cornuta was described by Darwin (1851: 165) based on specimens collected near St. Vincent in the Windward Islands, West Indies. It has since been found at depths of 125 to 750 m off the north- western coast of Africa (Broch, 1927: 16; Stubbings, 1964: 107; 1965: 880) and at a depth of about 90 m off the eastern coast of the United States (Ross et al., 1964: 312). I report here the occurrence of H. cornuta in the eastern Pacific, south of the Desventurados island group. This record is not unusual because many scalpelli.¿s have an amphiamerican distribution (see Newman & Ross, 1971). The individuals Nilsson-Cantell (1938: 237) reported as H. cornuta from the Indian Ocean are more than likely referable to H. japonica (Aurivillius, 1894) to judge from the development of the carinal protuberances. Heteralepas occurs pantropically and apparently reaches its greatest diversity in the Indo-West Pacific faunal province. Three species are known to occur in the eastern Pacific. Heteralepas quadrata (Aurivillius, 1894) was reported from . Baja California, Mexico (Gruvel, 1905: 159; Pilsbry, 1907b: 103), H. cygnus Pilsbry, 1907 from Monterey, California (Pilsbry, 1907b: 101), and H. mystaco- phora Newman, 1964 from the southwest end of Nasca Ridge (85°W 25°S; Zullo & Newman, 1964: 360). None of these species are easily confused with H. cornuta. HETERALEPADIDAENilsson-Cantell, 19211 - Remarks. A table for discriminating between Heteralepas and Paralepas, and a list of nominal species assigned to each genus, was presented by Newman (1960: 108). A familial diagnosis may be found in Newman, Zullo & Withers (1969: R278). Heteralepas Pilsbry, 1907 - Type species. Alepas rex Pilsbry (1907a: 186), by original designation; Recent, off Kauai Island, Hawaiian Islands, 417-430 m, on dead stems of gor- gonians. 18 Heteralepas cornuta (Darwin, 1851) Alepas cornuta Darwin, 1851: 165, pl. 3 fig. 6; Hoek, 1883: 56; Weltner, 1897: 239; Gruvel, 1905: 161, fig. 178. Heteralepa.r (Heteralepa.r) cornuta: Broch, 1927: 16, pl. 4 figs. 26-29, text-fig. 3. Heteralepas cornuta: Pilsbry, 1907b: 101; Nilsson-Cantell, 1921: 246; Nilsson-Cantell, 1927: 756; Newman, 1960 : 109; Stubbings, 1964: 107; Ross et al., 1964: 312; Stubbings, 1965: 880; Stubbings, 1967: 239. Material examined. - Two specimens, west of Carrizal Bajo and due south of the Islas de los Desventurados, Chile; 28°18'S 8OoO2'W;I.M.W., SG 17; 4235-4315 m; "Anton Bruun" Cruise 17, sample 677E; July (?) 1966; USNM No. 141612. Two specimens, off Cape Lookout, near Beaufort, North Carolina; 34°11'N 76°08'W; I.M.W., NI 18; 91 m; 8 October 1963. Eight specimens, off Ft. Lauderdale, Florida; 26°08'N 80'08'W; I.M.W., NG 17; 90 m; 1964. - Remarks. I did not detect any major morphological features in the large specimen I dissected that differentiate it from those specimens described and illustrated by Darwin (1851: 165) and Broch (1927: 16). In view of the dearth of published illustrations, pertinent aspects of the morphology of this species are illustrated in fig. 1. Because Darwin figured only the palp of this species, I am forced to compare the mouth parts of the present specimens with those of Broch. The labrum has about twenty-two teeth; a comparable number are found in the specimen that Broch figured. The dentition of the mandibles differs in that the superior slope and inferior margin of the second and third teeth are serrate, whereas Broch illustrates .this condition for only the second tooth. The Beaufort and Ft. Lauder- dale specimens I dissected are similar to the eastern Pacific ones in this regard. Maxilla I has seven spines above the medial notch and seventeen below. Both Darwin and Broch mention the presence of only three stout spines above the notch, but in the Beaufort specimens there are four to five and in those from Ft. Lauderdale there are five to seven. The cirral counts are in close agreement with those given by both Darwin and Broch, taking into account size differences. Cirral counts of the dissected specimen, which has a capitular height of about 4 mm, follow: Stubbings (1965: 881) presented measurements of the eggs from one African specimen. In view of the fact that he did not cite the exact locality for the speci- men from which the eggs were removed and the date of collection, and because of the absence of pertinent data relevant .to the collections available to me, I have .