OF CONCHOLOGY. 195 



Shell oblong ovate, but slightly elevated, green with a pale 

 or whitish line down the middle. The valves are semi-lunar in 

 shape, the posterior side being straightly transverse or nearly 

 so. They are without a ridge or umbonal elevation in the cen- 

 tre, where they are smooth ; the sides minutely granulose. The 

 valves of insertion are entire plates, on which the dorsal valves 

 are set or imbedded. They extend from the sides of the dorsal 

 valves, and produced anteriorly, the edges being smooth and 

 rounded at their termination. On the posterior terminal valve, 

 they are produced laterally, and are truncate at their termina- 

 tion. On the anterior terminal valve, they are produced at an 

 equal distance around the front and sides. They are smooth and 

 of a light bluish color. The ligamental border is covered with 

 close-set, short spicule. The spiculae of the tufts are dense, 

 vitreous and dark green. 



The above description will require to be revised and extended, 

 when mure perfect specimens t are found. 



(?) ACANTHOCHITES ARMATUS, Pse. 



T. ovata, vix oblonga, elevato-convexa, viridescens, nigres- 

 cente irregulariter maculata, medio pallida, nigrescentibus longi- 

 tudinaliter bilineata ; areis lateralibus granulosis, centralibus, 

 longitudinaliter stria lis, non umbonatus ; ligamento coriacea, an- 

 gusto, spiculis nitidis, albis, induto, et spicularum vitriorum cris- 

 tis argentaceo-albis munito. 



Long. 10, diarn 6 mill. Hab. Insl. Oahu. 



I have but a single specimen of this beautiful little species, the 

 valves of which are very much broken. It is somewhat elongate 

 in shape, elevately convex, light green, irregularly spotted with 

 blackish, paler along the middle, with two longitudinal blackish 

 lines. The lateral areas are distinctly granulose, central longi- 

 tudinally striate, without any umbonal elevation. The ligamental 

 border is narrow, and covered with shining white spiculse, and 

 furnished with a row of silvery white tufts of spiculse. 



