140 



As Reeve pointed out so long ago Pinna [Streptopinna) saccata is one of the most 

 variable species of the genus, and its shells are distorted into "ail sorts of forms; even shells 

 from the same locality vary in référence to the form, colour and texture of the shells". The 

 "Amber-red horny substance" of the shell, which Reeve considered as "quite peculiar" of the 

 species, is not by any means so, young shells are quite vvhite, thin and papery, but are connected 

 by intermediate forms with shells having the amber-red colour. The number of longitudinal ribs 

 and furrows is also very variable; in the spécimens before me it ranges between 6 — 20. Younger 

 shells are usually more regular in shape, being almost triangular and Pinna-\\V.ç., but older shells 

 become distorted and often assume very bizarre and contorted outlines. 



Distribution : — Bartsch ^) apparently following Linnaeus stated that P . {S.) saccata is 

 a Mediterranean species, but Linnaeus stated Mediterranean and Indian Océan as its range, 

 though the figures cited vvere apparently from the Indian Océan. Lamarck restricted its 

 distribution to the Indian Océan, and more récent workers, such as Winckworth hâve recorded 

 its rangre as the Indo-Pacific and the Red Sea. 



In the "Siboga" collection P. (5".) saccata is represented by spécimens from Anchorage 

 off Atjatuning, west coast of New Guinea (St. 169), Waru Bay, north coast of Ceram (St. 174), 

 St. 182 (3°46'S., i27°42'E.), Anchorage off Pasir Pandjang, west coast of Binongka (St. 220), 

 St. 225 (5700 M. N., 279° East from south Point of South Lucipara Island), Ambon Anchorage 

 (St. 231), Nalahia Bay, Nusa Laut Island (St. 234). 



Family Crassatellidae. 



Genus Crassatella Lamarck. 



1799. Crassatella Lamarck, Mém. Soc. d'Hist. Nat., Paris, p. 85. 



1801. Crassatella Lamarck, Syst. Anim. sans Vertèb., p. 119. 



1930. Crassatella Stewart, Spécial Publication Acad. Nat. Sci. Philadelphia, N'^ 3, p. 134. 



Dall and several other authors hâve replaced Crassatella Lamarck by Crassatellites 

 Krueger, as the figure cited by Lamarck in the first work cited above is that of a Mactra. 

 His description, however, is that of a Crassatella and he corrected the wrong citation in his 

 second work. I, therefore, agrée with Stewart that there is sufficient justification for accepting 

 Crassatella in préférence to Crassatellites \ the unsatisfactory nature of the latter name has also 

 been commented upon by Iredale ^). 



The génotype is Crassatella ponderosa (Gmelin). 



I. Crassatella picta Adams & Reeve. 



1850. Crassatella picta Adams & Reeve, "Samarang" MolL, p. 82, pi. XXIII, fig. 6. 

 1857. Crassatella picta Adams, H. & A., Gen. Rec. Moll., II, p. 486. 

 1860. Crassatella picta Reeve, Elem. Conch., II, p. 141. 



1886. Crassatella picta Loebbecke & Kobelt, in Martini-Chemn. Conch. -Cab. (N. F.), X [\a), 

 Crassatella, p. 18, pi. VI, fig. 8. 



1) Bartsch, P., Bull. U.S. Nat. Mus., XCI, p. 247 (1915). 



2) Iredale, T. — Proc. Malacol. Soc. I.ondon, XIV, p. 206 (1921). 



