42 BULLETIN^ 122, UNITED STATES NATIONAL MUSEUM. 



more abruptly dorsally than ventrally. -The spaces that separate 

 these ridges are wider on the early part than on the later. They are 

 about as wide as the ridges in the later portion. The anterior me- 

 dian portion is crossed by dental ridges which bear strong denticles, 

 and are separated by narrow impressed lines. They join the ridges 

 of the anterior portion in a little more than a right angle. The mid- 

 dle median portion is concave and crossed by rough incremental lines. 

 The posterior median portion is not quite as wide as the anterior and 

 middle portions combined, and is also crossed by curved, rough lines 

 of growth. The posterior part forms a very small auricle, which is 

 decidedly obliquely situated and scarcely differentiated from the pos- 

 terior median part. It is marked by the same rough lines of growth 

 characterizing the posterior median part. The interior is bluish 

 white. The junction of the anterior and median portions is 

 marked by a raised thread. The middle median portion has an irreg- 

 ular groove terminating in a basal knob. The very narrow oblique 

 auricle fuses with the posterior median portion, without suture. A 

 strong, broad, curved blade springs from the under side of the large 

 umbone and extends for about two-thirds of the way across the in- 

 side of the shell. The pallets are spoon shaped. The stalk is short 

 and irregularly curved. The junction of the blade and the stalk 

 forms a number of rings. The inside of the blade is smooth, except 

 at the edge where the periostracum is roughened. It shows the stalk 

 passing through the interior of the blade. The outside of the pallet 

 is very rough and scaly, marked by a series of concentric lines. 



The type. Cat. No. 216919, U.S.N.M., and a lot of additional mate- 

 rial was collected at the Naval Station at Guantanamo Bay, Cuba. 

 It measures : Height, 5.8 mm. ; length, 5.3 mm. ; diameter, 6 mm. The 

 pallets measure: Length, 6 mm., of which 1.3 mm. go to the stalk; 

 diameter, 3 mm. 



This species is readily distinguished from all the others by its 

 extremely narrow oblique auricle. 



TEREDO (PSILOTEREDO) JAMAICENSIS, new species. 

 JAMAICA SHIPTYOBM. 



Plate 29, fig. 1 ; plate 35, fig. 1. 



Shell subglobular, white. The anterior portion with the usual 

 sinus. The extreme anterior ventral margin forming a strongly drawn 

 out point. The callus is reflected over the shell and forms a rather 

 broad ridge, from the edge of which the dental ridges of the anterior 

 part radiate, although those more ventral bend first downward and 

 then backward. Of these ridges 79 can be counted in the type. These 

 ridges are about as wide, or a little wider, than the spaces that sepa- 

 rate them at the posterior termination, and the dorsal side is about 



