1 88 TYLODINA. 



T. AMERICANA Ball. PI. 50, figs. 47, 48. 



Shell rounded in front, subtruucate 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 T. amerieana. 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 T. Rafinesquim 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. S. 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 ?), DALL, ' Blake ' Gastropoda, 

 Bull. M. C. Z., xviii, p. 60, pi. 14, f. 9, 10 (1889). Tylodina amer- 

 ieana DALL, Nautilus, iii, 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 



