828 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxih 



PHACOIDES (LUCINISCA) NUTTALLII var. CENTRIFUGUS Ball. 

 (Plate XXXIX, fig. 13.) 



P. nuttallii is one of the most attractive of the West AmericaD 

 species. Its elegant reticulate sculpture is usually very evenly dis- 

 tributed. Some specimens from the Gulf of California, however, 

 ha^'e the concentric sculpture near the beaks more elevated and the 

 lamellae more widel}' separated, while the radial sculpture remains 

 unchanged, thus altering the appearance of the shell very materially, 

 especially in rather young specimens. The concentric ridges at the 

 intersections give out little flat unciform scales or spines, extremely 

 caducous and alwaj's lost in the adult. The general aspect of this 

 variety is so striking that I have thought it would be useful to name 

 and illustrate it. 



The figured specimen is from 26 fathoms, sandy nmd. in the Gulf of 

 California and measures 7 mm. in length. 



PHACOIDES (LUCINOMA) HEROICUS, new species. 

 (Plate XLI, fig. 1.) 



Shell large, moderately convex, chalky white, with a strong oliva- 

 ceous periostracum; beaks small, pointed, recurved, not much elevated; 

 dorsal areas indicated by a more emphatic flexuosity than is usual in 

 this group; sculpture of concentric, fine wrinkles and distant, con- 

 centric, sharp, elevated lamellae, continuous over the whole shell: 

 ligament long, strong, in a very shallow groove; lunule long, narrow, 

 rather deeply impressed, its periostracum darker than on other parts 

 of the shell; teeth slender, normal, a feeble anterior left lateral is vis- 

 ible; muscular impressions normal, margins not crenulated. Alt. 65, 

 Ion. 71, diam. 27 mm. 



This very fine abyssal shell is nearest to the P. (jequizonatux Stearns 

 (Plate XLI, figs. 2, 3), which is much smaller and more quadrate. 



PHACOIDES (PARVILUCINA) TENUISCULPTUS Carpenter. 



(Plate XL, fig. 5.) 



This unfigured species is now illustrated from a specimen from the 

 typical locality, Puget Sound, which has an altitude of 12 mm. 



This is one of the most abundant shells in Alaskan dredgings from 

 over a muddy bottom, usually in 10 to 20 fathoms. Its chalky shell 

 is almost invariably more or less abraded. 



PHACOIDES (PARVILUCINA) APPROXIMATUS, new species. 

 (Plate XXXIX, fig. \.) 

 Shell small, tumid, nearly equilateral, white with a yellowish perios- 

 tracum; beaks high, full, with a rather emphatically depressed lanceo- 

 late luniUe; sculpture of numerous fine, rounded, usually entire riblets 

 separated by narrow sulci on the disk, ])ut absent from the dorsal 

 areas; concentric sculpture of low. feeble, distant, elevated lines which 



