552 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



to the posterior ventral margin. From the under side of the rni,ddle 

 of this shelf the broad blade bends down toward the ventral knob. 

 It is the peculiar position of the blade in this instance which has 

 prompted me to give to this form a generic designation. Pallets 

 unknown. 



The type (Cat. No. 311281, U.S.N. M.) comes from a piece of wood 

 dredged at United States Bureau of Fisheries Station 5243, off 

 Uanivan Island Pujada Bay, Southeast Mindanao in 218 fathoms on 

 gray mud bottom. The type, the largest specimen, measures : Height, 

 4.2 mm.; length, 3.9 mm.; thickness, 4.2 mm. 



Cat. No. 311282, U.S.N.M., contains additional specimens which 

 were obtained at the same station. 



7TEREDO (subgenus?) MINDOROANA, new species 

 MINDORO SHIPWORM 



Plate 55, figs. 3, 5; plate 57, fig. 1 



Shell of medium size, subglobular, the anterior area with a rather 

 large sinus which is bordered by a slender callus that is reflected over 

 the anterior area at the edge. From this callus the dental ridges pass 

 first a little ventrally, then across the anterior area. They are closely 

 approximated at their anterior margin and separated by spaces a little 

 wider than the ridges at the posterior edge of the later part, and fully 

 twice if not three times as wide on the early part. Of these ridges 56 

 are present in the type, and many more have been eroded at the 

 umbone. They are very finely denticulated at their free margin. The 

 anterior median portion is very broad and marked by very broad den- 

 ticulated ridges w T hich are separated by very deep narrow channels. 

 Of these ridges 40 occur in a line projected across this area from the 

 ventral margin of the anterior part. The individual denticles are 

 doubly cusped, the anterior one being about twice as wide as the poste- 

 rior. The middle portion of the median part is slightly concave and 

 marked by the continuations of the dental ridges of the anterior portion 

 which are here bent and edentulous. They render this portion rather 

 rough in appearance. The posterior portion is about as wide as the 

 anterior portion of the middle part and is distinguished from the pos- 

 terior auricle by a deep constriction. It is marked by concentric lines 

 of growth which are parallel with its ventral margin in curving. The 

 posterior auricle is large and projects like a strong claw. It is marked 

 by conspicuous wavelike corrugations which agree with the ventral 

 margin in disposition. Interior bluish-white. A conspicuous cord 

 is present on the suture of the anterior and median part. The pos- 

 terior part is projected decidedly over the posterior portion of the 

 median part, almost half extending into the cavity of the shell. This 

 part is ear-shaped and its inner border is free and leaves a shallow 



