188 TYLODINA. 
T. AMERICANA Dall. PI. 50, figs. 47, 48. 
Shell rounded in front, subtruncate behind; thin, translucent 
yellowish, with a tint of orange near its apex; surface polished but 
irregularly malleated as if from irregularities of station; apex dis- 
proportionately pointed compared with the rest of the shell, erect, 
dwindling rapidly to a blunted point with a slight posterior tendency ; 
on the back of this is apparently an obscure scar as of a dehiscent 
embryonal tip or nucleus; apex about the beginning of the posterior 
third ; interior polished, anterior horns of the pedal muscles reach- 
ing about the anterior third united by a delicate arched line mark- 
ing the attachment of the mantle. Length 10, width 8, alt. 4 mill. 
(Dall). 
In my Report on the “ Blake” Gasteropods I have described and 
figured a shell, which, in the absence of the soft parts, I was obliged 
to refer doubtfully to the young of Umbraculum or Tylodina, under 
the head of “ Umbraculum bermudense Morch ?” 
This shell now proves to be a genuine Tylodina, different from the 
species of the Mediterranean or of California, and which may take 
the name of 7. americana. The shell, which was well figured as 
above, in life has a membranous extension 3-5 mill. wide around the 
margin, continuous with the epidermis. The latter is smooth and 
pale with radiating broad purplish rays of color. The animal 
is much smaller than that of 7. Rafinesqui in proportion to the shell, 
which abundantly covers it, and it emits a dark purple dye. It 
does not seem to differ essentially in the superficial characters of its 
soft parts from the species of the Mediterranean, which, however, has 
not been very well figured. The gill is attached to the edge of 
mantle on the right side. The other characters are much as stated 
in H, & A. Adams’ generic description. (Dall). 
Off Havana, dead, in 80 fathoms (‘ Blake’) ; northern border of the 
Gulf of Mexico (U. 8. Fish Commission at Station 2406), in 26 
fathoms, coarse sand and broken coral, on the line between the 
mouth of the Mississippi River and Cedar Keys, Florida; living. 
Umbraculum bermudense (Morch ?), Daun, ‘ Blake’ Gastropoda, 
Bull. M. C. Z., xviii, p. 60, pl. 14, f. 9,10 (1889).— Tylodina amer- 
icana Dau, Nautilus, ii, p. 121 (March, 1890). 
T. FuNGINA Gabb. 
Shell subelliptical, elevated, the apex subcentral, blunt; cuticle 
reddish-brown, yellowish on and near the apex, projecting. beyond 
