a vite . N AUC Gs: 
VOL. Il. MARCH, 1890. No. 1]. 
ON A NEW SPECIES OF TYLODINA 
BY WM. H. DALL. 
In my Report on the Blake Gasteropods I have (p. 60, pl. xiv, 
figs. 9, 10) described and figured a shell, which, in the absence of the 
soft parts, I was obliged to refer doubtfully to the young of Um- 
braculum or Tylodina, under the head of “ Umbraculum bermudense 
Morch?” 
This shell now proves to be a genuine Ty/lodina, 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 5—Jmm. 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 of the genus (Gen. Ree. 
Moll. II, 42). 
The Blake specimen was obtained off Havana, dead, in 80 fathoms. 
The present specimen was obtained on the northern border of the 
Gulf of Mexico by the 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. 
