Three New Species of Teredo 13 
entire shell, thin, narrow, the ventral end broadly 
reflected posteriorly. The ventral knob small, somewhat 
narrower than the supporting middle-median area. The 
anterior-median area bearing a thickened chord in the 
vicinity of the anterior area. The auricle extending over 
the posterior-median area in a heavy callous, ending in 
an abrupt deep ridge, but with no trace of a shelf. 
The pallet (fig. 18) with a very slender, delicate, 
translucent stalk. The stalk can be seen to extend 
dorsally a considerable distance through the long, nearly 
opaque enveloping sheath of the blade. The blade long, 
narrow, with the sides nearly straight, opaque, milk- 
white, covered with a very thin horn colored perios- 
tracum, which is very difficult to see excepting at the 
extreme distal end. The outer face convex, the inner flat. 
The distal end slightly cupped, with the outer face of 
the blade divided for half its entire length by a narrow, 
deep, sinus. 
The type (Mus. Comp. Zoél., 45307) is from Christian- 
sted, St. Croix, Virgin Islands. 
The measurements of the type are: 
Shell, height 3.5 mm.; length 3.5 mm. 
Pallets, total length 4 mm., equally divided between 
blade and stalk; width of blade, 0.9 mm. 
The shell of Teredo fulleri is very similar to that of 
other species of the subgenus Zopoteredo. It is perhaps 
most like that of Teredo johnsoni, from which it may be 
distinguished by the more obtuse angle formed by the 
anterior and anterior-median areas, the shell being mm 
this respect more nearly like that of Teredo clappi. The 
ridges of the anterior area are proportionately larger 
and the intervening spaces smaller. The internal ridge 
at the juncture of the anterior with the anterior-median 
area is constantly much more clearly marked in T. fullert 
