1 88 TYLODINA. 



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



Shell rounded in front, subtrimcate behind ; thin, transluceul 

 yellowish, with a tint of orange near its apex ; surface polished bui 

 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 dehisceu 

 embryonal tip or nucleus ; apex about the beginning of the posterioi 

 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 

 (Ball). 



In rny Report on the " Blake" Gasteropods I have described am 

 figured a shell, which, in the absence of the soft parts, I was obligee 

 to refer doubtfully to the young of Umbraculum or Tylodina, unde 

 the head of" Umbraculum bermudense Morch?" 



This shell now proves to be a genuine Tylodina, different from th< 

 species of the Mediterranean or of California, and which may taki 

 the name of T. americana. The shell, which was well figured a 

 above, in life has a membranous extension 3-5 mill, wide around tin 

 margin, continuous with the epidermis. The latter is smooth an< 

 pale with radiating broad purplish rays of color. The anima 

 is much smaller than that of T. Rafinesquiiu proportion to the shell 

 which abundantly covers it, and it emits a dark purple dye. I 

 does not seem to differ essentially in the superficial characters of it 

 soft parts from the species of the Mediterranean, which, however, ha 

 not been very well figured. The gill is attached to the edge o 

 mantle on the right side. The other characters are much as state( 

 in H. & A. Adams' generic description. (Dall). 



Off Havana, dead, in 80 fathoms (' Blake') ; northern border of th 

 Gulf of Mexico (U. S. Fish Commission at Station 2406), in 21 

 fathoms, coarse sand and broken coral, on the line between th 

 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 

 icana DALL, Nautilus, iii, p. 121 (March, 1890). 



T. FUNGINA Gabb. 



Shell subelliptical, elevated, the apex subcentral, blunt ; cuticl 

 reddish-brown, yellowish on and near the apex, projecting beyom 



