MUSEUM OF COMPAKATIVE ZOOLOGY. 181 



of the mantle; orifices of the combined generative organs behind and below 

 the right eye-peduncle. (See 3d SuppL, Plate VIII. Fig. A.) 



Jaw arcuate, with numerous ribs. (Plate IX. Fig. B of same.) 



Lingual membrane with tricuspid centrals, bicuspid laterals, and quadrate 

 denticulated marginals. (Plate IX. Fig. C of same.) 



Northwestern parts of North America, in the Oregon Region. 



Allied to Prophysaon, but distinguished by its more anterior respiratory 

 orifice, its rudimentary shell-plate, and decided caudal pore. 



Phenacarion foliolatus, Gould. 



Color a reddish fawn, coarsely and obliquely reticulated with slate-colored 

 lines, forming areolae, which are indented at the sides, when viewed by a mag- 

 nifier, so as to resemble leaflets; the mantle is concentrically mottled with 

 slate-color, and the projecting border of the foot is also obliquely lineated. 

 The body is rather depressed, nearly uniform throughout, and somewhat trun- 

 cated at the tip, exhibiting a conspicuous pit, which was probably occupied by 

 a mucus gland. The mantle is very long, smooth, and has the respiratory ori- 

 fice very small, situated a little in front of the middle. The eye-peduncles are 

 small and short. Length 85 mm. 



Arion foliolatus, Gould, Moll. U. S. Exp., page 2, Fig. 2, a, b (1852); Binxey, 

 Terr. Moll., II. 30, Plate LXVI. Fig. 2(1851); W. G. Binxey, Terr. 

 Moll., IV. 6 ; copied also by Trton and W. G. Binnet, L. & Fr. \V. 

 Sh., I. 877. 



Phenacarion foliolatus, Cockerell, The Nautilus, 1890, III. 126; W. G. Binnet, 

 3d Suppl. to Terr. Moll. V., p. 206, Plate VIII. Fig. A ; Fig. B (shell- 

 plate) ; Plate IX. Fig. B (jaw); Fig. C (dentition); Fig. D (genitalia). 



Discovery Harbor, Puget Sound (Pickering) ; Olympia and Seattle, Wash- 

 ington (Hemphill). 



Dr. Gould adds to the above description these words (Vol. II. p. 31) : " That 

 this animal belongs to the genus Arion there can be little doubt, from the 

 peculiar structure of the tail, as represented in Mr. Drayton's figure, and from 

 the anterior position of the respiratory orifice. It is a well marked species, 

 characterized especially by the leaf-like areolae by which the surface is 

 marked." 



It is with the greatest pleasure that I announce the rediscovery by Mr. 

 Henry Hemphill of this species, which has hitherto escaped all search by 

 recent collectors. It has till now been kno^vn to us only by the description 

 and figure of the specimen collected by the Wilkes Exploring Expedition, 

 almost fifty years ago, and given in Vols. II. and III. of Terrestrial Mollusks. 

 A single individual was found in December, 1889, at Olympia, Washington, 

 and sent to me living by Mr. Hemphill. It can tlius be described. (See 

 Fig. A of Plate VIII. of 3d Suppl.) 



Animal in motion fully extended over 100 millimeters. Color a reddish 



