AET. 15 NEW AUSTRALIAIsr LAND SHELLS MARSHALL 13 



Murray Islands, Torres Strait, and was presented by Mr. C. Walton, 

 in whose honor the species is named. 



Mr. Walton presented seven other specimens of this species from 

 the same locality (Cat. No. 333817 and 333820, U.S.N.M.). Three 

 of these are immature; one is abnormal in that it has the whorls 

 rounded, and each slightly sunken into the succeeding whorl, has the 

 periphery rounded instead of angular, and is distinctly spirally 

 striate on the body whorl near the suture; the other two specimens 

 are similar to the type but smaller. 



The pale colors, flattened whorls, angular periphery and peculiar 

 peristome, sharp at its upper portion and widely reflected from the 

 peripheral angle to the umbilicus, make this one of most distinct 

 species of the fauna of Torres Strait. 



THERSITES (HADRA) DALLI, new species 



Plate 2, fig. 8 



Shell turbinate-conical, thin, rather elevated; whorls 6%, slightly 

 convex, each appearing to be a little sunken into the succeeding 

 whorl. Body whorl suddenly bent down near the aperture; pe- 

 riphery moderateljT^ angulated on the back of the body whorl, 

 strongly angulated in front of the aperture, the outer lip showing 

 scarcely any sign of being affected by the angle of the periphery. 

 Sculpture of many slightly retractive growth riblets and a micro- 

 scopic reticulation of fine lines. Sutures well impressed, somewhat 

 crenulated by the upper ends of the growth riblets. Base convex, 

 its depth slightly less than the height of the spire. Umbilicus wide, 

 largely concealed by the reflected columellar lip. Aperture rounded, 

 upper portion of the peristome simple, scarcely reflected ; beginning 

 to expand at the periphery until at the columella it is very broadly 

 reflected and conceals a large part of the umbilicus. Parietal wall 

 with a moderately thick glaze. Color of entire shell tawny, the base 

 very slightly darker than the spire ; an indistinct whitish band mark- 

 ing the periphery. 



The type (Cat. No. 100176, U.S.N.M.) measures: Greater diameter, 

 44 mm. ; lesser diameter, 38 mm. ; height, 30.5 mm. It and a para- 

 type (Cat. No. 333818, U.S.N.M.) were received from R. E. C. 

 Stearns to whom they were sent by Dr. J, C. Cox, with the label 

 ''''Helix {Gamaenxi) semicastanea Pfeiffer; northeast Australia." 

 These specimens show the wide range of variation allowed by Doctor 

 Cox in his identifications of Thersites semicastanea. They bear 

 but little resemblance to that species. They are closely related to 

 Thersites loaltoTd Marshall in color, texture, and general form, but 

 differ from it in being smaller, less angular at the periphery, more 

 elevated, with the whorls slightly more rounded, and in having the 



