6 PEOCEEDHSTGS OF THE NATIONAL MUSEUM vol.72 



columellar lip, the peristome thicker and less expanded, a heavy- 

 callus across the parietal wall joining the two ends of the peristome. 

 Colors much lighter but distinctly bipartite, the spire pale yellowish 

 white, the base faded chestnut. 



The type (Cat. No. 317033, U.S.N.M.) measures: Greater diameter, 

 33 mm. ; lesser diameter, 28.5 mm. ; height, 22,5 mm. It and a para- 

 type (Cat. No. 333T93, U.S.N.M.) are part of the Henderson collec- 

 tion and come from Lizard Island on the east coast of Queens- 

 land, Australia. 



While the condition of the interior of these two specimens show 

 that they were " living " shells when collected, the pale colors of the 

 spire and base seem to be due mostly to loss of nearly all the perio- 

 stracum, though a few remaining vestiges of periostracum show that 

 the shell was naturally of very light colors. At first glance this 

 subspecies bears a resemblance to T. hipcm'tita^ but careful compari- 

 son with that species and with T. lizcerdeTisis shows that it is more 

 closely related to the latter. 



THERSITES (HADRA) SEMICASTANEA SEMICASTANEA Pfeiffer 



Plate 2, fig. 5 



1849. Helix semicastanea Pfeiffer Zeitsch. fur Malak., vol. 6, p. 77; in 

 Chemnitz Conch. Cab. ed. 2, Helix, no. 319, plate 56, figs. 3-5 (title page 

 dated 1846, but the species is quoted from the Zeitschrift for 1849, thus 

 showing that it was described in that year). 



Shell small, rather thin, depressed conic, whorls from 5l^ to 6 in 

 number, slowly increasing, slightly convex, body whorl rounded, 

 but just in front of the aperture it is somewhat angular showing 

 that the concealed periphery of the earlier whorls was angular. 

 Surface with numerous retractive growth striae and surface mi- 

 nutely reticulate, with faint indications here and there of spiral 

 striae. Base convex, umbilicus rather narrow. Aperture rounded, 

 scarcely oblique. Peristome thin, reflected, its columellar portion 

 partially concealing the umbilicus. Parietal wall glazed. Color 

 reddish, the base darker than the spire and glossy, a spiral white or 

 whitish band at the periphery. Interior showing the two shades of 

 the exterior and the white line dividing them. Sutures well im- 

 pressed, irregularly crenulated, marked by a dark line below and a 

 whitish line above. A very slight descent of the body whorl at the 

 aperture. 



The figured specimen (Cat. No. 169124, U,S.N,M.) measures: 

 Greater diameter, 34,5 mm, ; lesser diameter, 30 mm. ; height, 23 mm. 

 Another specimen with the same catalogue number, exactly like the 

 type but smaller, measures: Major diameter, 28 mm.; minor diam- 

 eter, 24 mm.; height, 19.5 mm. They are labeled "Queensland, 

 Australia," and were presented by Mr. S. W. Jackson. Cat. No. 

 100033, U.S,N,M., includes two specimens received from R. E. C. 



