AMPHIDROMUS, GROUP XVIII. 225 



noticeably angular in front. Aperture marked within, the lip thin, 

 white. 



Length 27, diam. 15 mill. 



Length 221, diam. 12 mill. 



Labuan Island, off north coast of Borneo. 



A. hamaJtus FULTON, Ann. Mag. N. H. (6), xvii, p. 84, pi. 5, f. 

 13 (Jan. 1896). Bulimus adamsi, var. E and F, ISSEL, Molluschi 

 Borneensi, in Annali del Museo Civico di Storia Naturale di Geneva, 

 vi, p. 413, pi. 5, f. 28, 29 (1874). 



Rather more fragile than adamsi, but differing chiefly in the dif- 

 ferent development and variations of the color-pattern. It has not 

 the three yellow bands so frequent in adamsi. The flames along the 

 periphery are usually hooked, from which character the name was 

 given. , 



In the large series before me there is every gradation between 

 uniform yellow or fleshy specimens and elaborately striped and 

 banded. Beginning with examples striped above and one or two 

 banded below (fig. 51), the pattern changes by loss of the narrow 

 stripes on the upper surface, then diminution of the peripheral 

 hooked flames (figs. 53-57), and finally narrowing and disappear- 

 ance of the spiral bands (fig. 58). Enough figures are given to show 

 the chief stages in the loss of brown pattern, but in the series before 

 me the change is seen to progress by such gradual steps that it would 

 be absurd to define ''varieties." 



This Labuan form was first noticed by Issel, who gives two good 

 figures. Schepman has noted the occurrence of a similarly marked 

 specimen collected by the Dutch Borneo-Expedition at Sintang 

 (Notes Leyden Mus. 1895, xvii, p. 156), where one would expect 

 the forms of subsp. pictus ; but doubtless the Sintang form is what 

 von Martens records from Mandhor, as transitions between the spot- 

 girdle form and that with wide green-gray stripes. 



PI. 70, fig. 60, is Fulton's type of hamatas. 



Form placidus Fulton. PI. 70, fig. 64. 



" Shell sinistral, broadly conical, slightly perforate, thin, obliquely 

 striate, somewhat angulate at the periphery; whorls 6, slightly con- 

 vex, apex brown, apical whorls white, lower of a pale lemon color; 

 columella straight, rather thin, slightly expanded, white at upper 

 part; lip pale purple-brown, expanded and slightly reflected. Long. 

 31 mill., maj. diam. 16 mill." (Fulton). East Borneo, 



15 



