110 BULLETIN 68^ UNITED STATES NATIONAL MUSEUM. 



Aperture oval; posterior angle acute; outer lip thin, showing the 

 external sculpture within; columella slender and somewhat sinuous. 

 The above description is based upon two cotypes which, together 

 with a third specimen, w^ere obtained at U.S. Bureau of Fisheries sta- 

 tion 2822 in 21 fathoms, off La Paz, Lower California. They are 

 entered as Cat. no. 206881, U.S.N.M. One of the two cotypes has 

 the nucleus and nine post-nuclear whorls and measures: Length 3.6 

 mm., diameter 0.8 mm.; the other has lost the nucleus and probably 

 the first four post-nuclear whorls, the seven remaining measure: 

 Length 4.3 mm., diameter 1.2 mm. 



Subgenus MORMITLA A. Adams. 



Morinula A. Adams, Journ. Linn. Soc. London, vol. 7, 1864, p. \;-\-Pyrgostylus 

 MoNTEROSATO, II. Nat. Hist. Sicil., 1884, p. 90. Type, Turbo striatulus 

 Linnaeus. 



Turbonillas having axial ribs and deeply incised spiral lines; also 

 irregularly disposed varices on the outer surface, which usually mark 

 internal lirations on the outer lip, or internal lirations of the outer 

 lip only. Sculpture never nodulose. 



Tyi^e. — Mormula rissoina A. Adams. 



KEY TO THE SPECIES OF THE SUBGENUS MORMULA. 



Varices present on the outside of the whorls. 

 Adult shell more than 16 mm. long. 



Shell conspicuously banded lordi, p. 111. 



Shell not conspicuously banded. 



Strongly incised lines between sutures 6, axial ribs 18-40. . .regina, p. 112. 

 Strongly incised lines between sutures 9, axial ribs 16-28. cataKnensis, p. 113. 

 Strongly incised lines between sutures 12, axial ribs 16-26 .eschscholtzi,p. 113. 

 Adult shell less than 13 mm. long. 

 Shell brown. 



Strongly incised lines between sutures 5, axial ribs 16-24 . tridentata, p. 114. 

 Strongly incised lines between sutures 10, axial ribs 1%~22 .amhusta, p. 115. 

 Shell white. 



Shell large, adult more than 9 mm. long major, p. 116. 



Shell small, adult less than 4 mm. long santosana, p. 117. 



Varices absent on the outside of the shell. 

 Spiral sculpture strong. 

 Shell brown. 



Adult shell more than 8 mm. long pentalopha, p. 117. 



Adult shell less than 6 mm. long heterolopha, p. 118. 



Shell white ignada, p. 119. 



Spiral sculpture absent or microscopic. 



^Vhorls shouldered periscelida, p. 119. 



WTiorls not shouldered phalera, p. 120. 



