452 BULLETIN OF THE 



augmented by the new discoveries of the past three years, may be expressed in 

 brief as follows : — 



Family Cuspidariidm : abranchiate, siphoseptate, septum foraminate. 

 Genus Cuspidaria (etc.) with long siphons; oral palpi obsolete. 

 Genus Myonera, short siphons ; oral palpi absent. 



Family Poromyidce : septibranchiate, siphoseptate. 

 Genus Poromya:. teeth strong; oral palpi large; foramina of septum slit-like, 

 between the close-set lamellae, arranged in two interrupted longitudinal 

 series; pallial sinus obsolete; surface of shell granular. 

 Subgenus Dermatomya: shell not granular; pallial sinus developed; hinge 



strong. 

 Subgenus Cetomya: shell granulous; pallial sinus obsolete; hinge teeth 

 obsolete in the adult. 

 Genus Cetoconcha: hinge teeth obsolete in the adult; pallial sinus obsolete; 

 siphoseptum foraminate, the foramina arranged in four longitudinal 

 series, solitary, the subtubular lips filling the office of gills. 

 Family Verticordiidce : siphoseptate with small adnate ctenidia; oral palpi 

 almost obsolete; septum imperforate. 



Lyonsia and probably Lyonsiella may be called branchioseptate, and should 

 be referred elsewhere. 



ADDENDA TO PAET II 



Intra-capsular Development of the Shell in Scaphella (II. p. 149, IT 3). 

 After this suggestion had been some time printed, I received from the collec- 

 tions of the Albatross on her voyage from Chesapeake Bay to California, some 

 ovicapsules of Scaphella magellanica from the coast of Patagonia. 



These ovicapsules are circular, about an inch (25.0 mm.) in diameter, with 

 a flat base attached to dead Pectens ; the upper part consists of a rounded 

 dome, rather more lenticular than hemispherical, but varying somewhat in 

 different specimens. It is exactly like the ovicapsule of Volatopsis from 

 Alaska, externally, and, like that, contains two to four surviving larval shells. 

 These remain in the capsule until they have three or four shelly whorls. The 

 apical point is acutely conical, slightly twisted, and in the youngest specimens 

 (two-whorled) still retains some shreds of the extremely fragile membranous 

 protoconch adhering to the first whorl. As suggested by me from a study of 

 the nuclei of Aurinia, the pillar of the protoconch and the apical spur of the 

 larval shell coincide. The shape of the protoconch could not be ascertained, 

 but its aperture was probably oval, from its traces left on the shelly surface. 

 The apex is at first very sharp, but it loses substance even in the ovicapsule, 

 and three-whorled specimens had it quite blunted, while shells escaped from 



