NO. 2134. NOTES ON CHRYSODOMUS—DALL. 227 



This species belongs to the group of P. yessoensis Schrenck {man- 

 churicus E. A. Smith) but is much larger than that species, the perios- 

 tracum lighter and jjolished, the canal relatively longer, and the 

 whole shell relatively more slender. 



PLICIFUSUS (ATJLACOFUSUS) RHYSSOIDES, new species. 



Shell slender, fusiform, vrith an olivaceous periostracum, and about 

 seven whorls, nucleus more or less eroded but apparently globose 

 and blunt; penultimate whorl with thirteen retractively arcuate 

 rounded plications with about equal interspaces, extending from 

 suture to suture and obsolete on the periphery of the last whorl ; the 

 suture distinct but not constricted; spiral sculpture of fine equal 

 close-set rounded threads, about three to a millimeter, slightly sparser 

 toward the canal; aperture semilunate, white within, the outer lip 

 slightly expanded; canal short, wide, recurved; the pillar white, 

 slightly arcuate, erased, obliquely truncate in front, the siphonal 

 f asciole faint. Length of shell 49 ; of last whorl 30 ; of aperture 20 ; 

 maximum diameter of last whorl 18 mm. 



Habitat. — Rikuzen, Japan. Hirase collection. Cotype, U. S. Nat. 

 Mus., Cat. No. 274069. 



The operculum is thin, pale yellowish-brown, the apex strongly 

 incurved. This species is quite close to P. rhyssus Dall, from which 

 it differs in its more fusiform shape, less inflated whorls, less con- 

 stricted suture, and, in the specimens available, lighter colored perios- 

 tracum. The incurvation of the apex of the operculum suggests an 

 approach toward Mohnia. 



PLICIFUSUS (LATIFUSUS) WAKASANUS, new species. 



Shell of moderate size, thin and light, covered by a yellowish- 

 brown smooth periostracum, with six moderately rounded whorls 

 without the (lacking) nucleus; suture distinct, not appressed; whorls 

 axially sculptured with (on the penultimate whorl 15-18) retrac- 

 tively arcuate plications, strongest near the suture, barely crossing 

 the periphery, and becoming gradually obsolete on the last whorl; 

 the plications are rounded, not sharply defined, and have about equal 

 interspaces; spiral sculpture of numerous equal flattish threads with 

 narrower interspaces, about three threads to a millimeter, this sculp- 

 ture covering evenly the whole surface ; aperture semilunate, interior 

 and pillar white; outer lip slightly expanded, pillar straight, an- 

 teriorly obliquely truncate; canal short, recurved, with no marked 

 siphonal f asciole. Length of shell 40; of last whorl 28; of aper- 

 ture 18; maximum diameter of last whorl 17 mm. 



Habitat. — Wakasa, Sea of Japan. Hirase collection. 



This belongs to the group represented on the American coast by 

 PUdfus'us (Latificsus) griseus Dall. 



