XYLOTRYA. 



35 



X. fimbriata. 



Xi/lotri/a Jimbriata, Jeffreys, Ann. and Mag. Nat. Hist. 3cl sor. vi. 126. — Tryon, Proc. 



Acad. N. Sf. Philad. xiii. -t7S (Sc'iit. 1S62). 

 Xjlotrya palmalata, y-riMrsoN, Smith. Inst. Check. Lists, 3 (1860). "■•'" i 



Shell greenish, subtrigonal, greatest height and length about equal 

 (length sometimes greater), anterior triangular projection as high 

 as the umbo, tip ascending, re-entering an- 



^ Fig. 361. 



gle about 90° ; anterior marginal area broad 

 above, sloping strongly inwards, and sepa- 

 rated from the posterior area by a sharp, 

 prominent angle, to which succeeds a nar- 

 row, shallow groove, bisected by a faint line ; 

 ribs on the triangular auricle and anterior 

 area about thirty, nearly equal in width, those 

 of the auricle finely crenulated at the sides 

 and faintly striated across ; those of the mar- 

 ginal area more coarsely cancellate by trans- 

 verse ribs extending down into the groove ; posterior auricle rather 

 large, the upper margin sloping gently from the hinge and then, 

 slightly excurved and recurved, ends by an obtuse notch at the 

 lower third of the claw and far below the anterior triangle ; it is also 

 separated from the claw by a w^ell-marked groove ; its internal face 

 is nearly as large as the rest of the shell, narrow near the umbo, 

 gradually expanding, with an oblique termination, concave and con- 

 centrically striate, the lower margin nearly straight, sharp, and 

 slightly detached from the claw. Ossicle at tip small. Hinge tooth 

 small ; umbonal blade falcate, tapering, compressed, sharp-edged. 

 Pallets oar-shaped, the blade as long and about three times as wide 

 as the slender, pointed handle, composed of ten or twelve joints 

 shorter than broad, the divisions nearly transverse on the convex 

 side, but inclined backward on the flat side so as to appear braided 

 and a'ive the margin a serrated outline. 



Diameters about one fourth of an inch. Pallets half an inch long. 



Taken from one of the timbers of " Old Ironsides," which may of 

 itself constitute a sufficient claim to be reckoned a Massachusetts 

 shell, though probably not native. 



As noted l)y other describers, the shell itself is so nearly like that 

 of the true Teredo navalis as to be scarcely distinguishable. The 

 pallets, however, are altogether different. As represented by others, 

 the pallets have the braided or feather-like jointing on both faces. 

 The variation in this may in fact entitle it to a specific distinc- 

 tion, and, were the pallets not subject to wide variation, would cer- 



