60 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 20 



7. Shell rather solid without bright colors, 

 periostracum thick with solid hairs, 



shell color typically reddish-violet modiolus (Linne) 



Shell rather thin, often with color rays 

 posteriorly, periostracum light brown, 

 thin, with adherent sand grains and 

 shell particles, finer and broader hairs americanus (Leach) 



Modiolus capax (Conrad) 1837 

 Plate 6, fig. 30 ; text-figs. SO, 53 a-b, 54, 55 



Modiola capax Conrad, Jour. Acad. Nat. Sci. Phila., vol. 7, 1837, p. 242. 

 Syn.: f Modiola spatula Menke 1849. 



Modiola subfuscata Clessin 1889. 

 Holotype: Academy of Natural Sciences, Philadelphia? 

 Type loc: San Diego, California. 



Remarks: This species, in spite of the variable form, is always easily 

 recognized by the serrate hairs on the periostracum, and by the left valve, 

 which is usually more inflated than the right one, the difference being 



Fig, 47. Modiolus modiolus (Linne). The stippled anterior part 

 indicates the lunule. 



Fig. 48. Modiolus modiolus (Linne). Anterior part seen in an obli- 

 que view. Anterior retractor in the umbonal cavity behind 

 the umbo. The tooth-like projection of the anterior margin 

 behind the umbo is usually still more distinct. 



Fig. 49. Modiolus neglectus n. sp. Long Beach, California. The 

 interior with muscle scars. 



Fig. 50. Modiolus capax (Conrad). Posterior part seen from be- 

 hind. 



Fig. 51. Modiolus neglectus n. sp. Long Beach, Calif. Posterior part 

 seen from behind. 



Fig. 52. Modiolus modiolus (Linne). Aleutian Islands. Posterior 

 part seen from behind. 



Fig. 53. a.b. Mo^io/wj capax (Conrad). Puerto Refugio, Isla Angel 

 de la Guarda, Gulf of California. Two different perio- 

 stracum hairs from one specimen. 



Fig. 54. Modiolus capax (Conrad). Sulphur Rock, Puerto San 

 Bartolome, Baja California. Periostracum hair. 



Fig. 55. Modiolus sp. (perhaps capax Conrad). Santa Catalina 

 Island, California. Periostracum hair of a peculiar type. 



Fig. 56. Modiolus americanus (Leach). Yz mile SE of Punta 

 Hughes, Bahia de Santa Maria. Periostracum hair. 



Fig. 57 a.b. Mo^io/mj sacculifer (Berry), San Miguel. Two types of 

 periostracum hairs from one specimen. 



Fig. 58. Modiolus sacculifer (Berry). S. of Pillar Point, Halfmoon 

 Bay, California. Periostracum hair. 



Fig. 59, Modiolus neglectus n.sp. Long Beach, California. Perio- 

 stracum hair. 



