MITEULAUIA. 13? 



The oblique undulating ribs of the original figures, reproduced 

 by me, are not of specific importance, resulting from a similarly 

 sculptured surface of attachment ; they do not exist on other 

 specimens. The species is mainly characterized b}- its attenu- 

 ated apex, thinness and color. 



H. TicAONicus, Sowb. PL 41, figs. 23, 24. 



Suborbicular, with the apex posterior and recurved, closely 



vadiately striate, whitish, under a pale fulvous liairj^ epidermis. 



Length, 15 mill. 



I doubt its distinctness from H. subrufus, Sowb. 



Philippines. 



H. RUGULOSus, Dunker (unfigured). Samoan Is. 



H. PLANATUS, Carpenter (unfigured). Mazatlan. 



H. EFFODiENS, Carpenter (unfigured). West Indies. 



H. MINOR, Garrett (unfigured). Sandwich Islands. 



Genus MITRULARIA, Schum., ISlt. 



M. EQUESTRis, Linn. PI. 41, figs. 25-32 ; PI. 42, figs. 33-56 ; PI. 

 43, figs. 57-67, 70. 

 Nearly orbicular or irregular, rather solid, var3'ing to papy- 

 raceous, rudel}' convex ; whitish, or more or less stained with 

 light yellowish ; radiately closely minutely ridged, or striated, 

 outer edge of base often closel}^ crenulated. Basal plate con- 

 cave, platter-shaped, with puckered edge. Diam. 1-25 inches. 

 China Sea^ Philippines, Indian Ocean, 



Princess Isl., W. Africa, W. Indies^ 



W. Coast of Central Aynerica, Galapagos Is. 

 I have inteipreted this species in accordance with general 

 usage, the Linnoan species being indeterminable. The 83'nonomy 

 includes: ? 71/. Dillwynii, Gray, M. umbo, Reeve (fig. 27), M. 

 Neptunii, Dillw., var. costata, Morch, M. scutulum. Reeve (figs. 

 28, 29), 3L Stella, Reeve (fig. 31), 31. cepacea, Brod. (fig. 30), 

 M. varia, Brod. (fig. 35), M. Layardii, Reeve (fig. 33), M. 

 Adamsi, Reeve (fig. 36) = M. dejjressa, Ad. and Reeve, not 

 Lamarck (fossil sp.), M. alveolata, A. Ad. (fig. 34), 31. Vani- 

 korensis, Quoy (fig. 38), M. cancellata, Ad. and Reeve (fig. 37), 



