28 Proceedings of the Biological Society of Washington. 



from the inside of which the slender blade curves downward into the cavity 

 of the shell. This blade has its broad side obliquely placed to the inner 

 curvature of the shell. The anterior portion is separated from the median 

 by a thickened cord, and a roughened area marks the middle median portion 

 of the shell. The posterior area projects over the posterior median por- 

 tion as a shelf. The pallettes are of the cone-in-cone type, the distal 

 margin of the cones being entire. 



The type, Cat. No. 194,176a, and a lot of additional specimens, were col- 

 lected by Mr. C. R. Orcutt on dead mangroves at Sinaloa, Mexico. The 

 type measures: length, 7 mm.; altitude, 6.5 mm. The pallettes are all 

 fragmentary, and hence it is. impossible to give their measurement. 



Teredo (Teredo) parksi, new species. 



Shell subglobular, milk white; interior bluish white. The anterior por- 

 tion is edged by a thick, decidedly curved callus-like smoothish area, from 

 which the dental ridges curve at first downward and then gradually and 

 steadily outward, forming almost straight lines for the major portion of 

 their length. These dental ridges are a little narrower than the spaces that 

 separate them, and are of triangular shape, sloping a little more gently 

 ventrally than dorsally. The extreme edge is exceedingly, finely denticu- 

 lated. The posterior edge of the anterior portion joins the anterior edge 

 of the median portion in such a way that the dental ridges of the two form 

 almost right angles. About ninety-five of these dental ridges can be counted 

 on the anterior part. The anterior median portion is crossed by slender 

 dental ridges, which are separated by very narrow grooves and bear rather 

 prominent denticles. The erosion of the^umbone makes it impossible to 

 see exactly how many of these dental ridges occur, but there must be at 

 least as many as we found on the anterior part. The middle median por- 

 tion is a narrow roughened zone extending from the umbones to the ventral 

 margin, which is not concave, as is usually the case. The posterior part of 

 the median portion is marked by rather strong irregular upward curved 

 lines of growth. The posterior portion forms a short auricle, which is 

 crossed by rather regular lirations, which are really intensified lines of 

 growth that coincide with the outer margin in disposition. In the interior 

 a somewhat thickened ridge marks the junction of the anterior and median 

 portions. The middle median portion is marked by a strong, irregular 

 roughened area, while the posterior portion overlaps the posterior median 

 portion in such a way as to form a slight shelf having a decided cavity be- 

 hind it. A strong, flattened, broad, rough, irregular blade extends two-thirds 

 of the distance from behind the knoblike umbones toward the ventral edge 

 of the shell. The outer border of this blade keeps almost at an even dis- 

 tance from the shell. The basal portion of the median part has a strong 

 knob which extends as a thickening for some little distance into the interior 

 of the shell. The pallettes are spatulate, having a very long, very slightly 

 curved flexuous stalk, the spatulate portion being decidedly excavated at 

 the tip, and covered with a brown epidermis. The siphons in this species 

 are almost equal and project in the alcoholic material about half the length 



