122 AXEL A. OLSSON 



Specimens from Ecuador agree well with the figure of S. puntarenensis 

 given by Soot-Ryen, based on a paratype in the San Diego Museum (Chace 

 Coll.), My shells show much variation in shape and in coarseness of sculp- 

 ture and in some cases approach S. adamsianus quite closely. S. houstonius 

 Bartsch and Rehder, 1939 from Galapagos Islands is also similar. 



Range — Costa Rica to Ecuador and northern Peru. Ecuador: Jipijapa 

 (Puerto Callo). Peru: Yasila, Paita. 



ScoUmytilus (Aeldlmytilns) mnltiformis (Carpenter) Plate 17, figure 11 



Myiilus multiformis Carpenter, 1855, Cat. Mazatlan Shells, Brit. Mus., pp. 118-120, No. 

 168 Mazatlan. — Hertlein and Strong, 1946, Zoologica, vol. 31, pt. 2, p. 70 dis- 

 cussion with adamsianus. 



Brachidontes multiformis (Carpenter), Soot-Ryen, 1955, Allan Hancock Pacific Expedi- 

 tions, pp. 44, 45, pi. 3, fig. 13; text-fig. 28. 



Because S. mtdtiformis was not figured by Carpenter, its identification is 

 not entirely certain. In his remarks on the species, Carpenter emphasized 

 the extreme variability of the shell both in shape and sculpture. His un- 

 published manuscript drawings at the U. S. National Museum comprise 

 about 11 sketches, all of which are based on small or immature specimens. 

 These drawings show a small, short, fan-shaped shell with a large, smooth, 

 nepionic area followed by two or more sculptured areas setoff sharply from 

 each other and the nepionic disk by resting lines; the umbonal ridge is 

 low, rounded, not angular, and the ventral side is not noticeably impressed; 

 the scar of the ligament is only about half the length of the dorsal margin 

 which is strongly crenulated. The largest specimen measured by Carpenter 

 has a length of .45 inches or 11.4 mm.; this is probably the specimen num- 

 bered 551 and is here selected as the lectotype; a new figure based on 

 Carpenter's drawing is here given. 



A few of the Ecuadorian shells are tentatively identified with Car- 

 penter's species but they differ by the smaller nepionic area, which 

 in some cases can be seen only on high magnification. General color 

 black or dark-brown, not green. 



Range — Lower California to northern Peru. Mexico: Mazatlan (Car- 

 penter). Ecuador: Punta Callo; Santa Elena. Peru: Yasila. 



Genus SEPTIFER Recluz, 1848 



Type species by subsequent designation, Stoliczka, 1871, S. bilocidaris 

 Linne. 



Shell generally short, modioliform, with a high umbonal angle, the 

 external surface sculptured with small radial riblets, often with bristles. 

 Hinge and posterior margins strongly crenulated, the short anterior side 

 with small dysodont teeth as in Brachidontes and with a small deck or 

 platform placed like a shelf in the umbonal cavity below the beaks. 



Septlfer zetekl Hertlein and Strong Plate 13. figures 7. 7a 



Septifer cumingii Recluz. As cited by authors from West America localities but not 

 the true S. cumingii described from the island of Annaa. 



