HELIX-LAOMA. 57 



L. ISSERICA Kobelt. PL 21, figs. 12, 13, 14. 



Shell depressed-trochoidal umbilicate, or having the umbilicus 

 more or less covered, or entirely so ; periphery angulate, base a 

 little convex. Solid, chalky, striatulate, rather shining, white or 

 yellowish-white. Spire conoid, the apex peculiarly exserted. 

 Whorls 6, those of the apex convex, the following flat, lightly 

 impressed above the suture, forming a keel, which the impressed, 

 slightly crenulated suture follows ; last whorl inflated but scarcely 

 dilated, angulate-carinated, convex above and below: no umbilical 

 angle ; at the aperture the whorl descends suddenly and deeply. 

 Aperture very oblique, ovate-angulate, moderately lunate, margins 

 somewhat approaching, joined by a very thin callus; upper mar- 

 gin straight, produced, acute, forming an angle with the scarcely 

 reflexed outer lip, basal lip thickened, a little reflexed, dilated over 

 the umbilicus at the insertion. Alt. 15-18, diam. greater 21 2-24, 

 lesser 18-1-21 mill. (Kob.} 



Tizi R'rir, at the passage of the oriental Isser, below Palestro. 



Leucochroa isseriea KOB., Icon. Land u. Siisswasser-Moll. (n. f.), 

 iii, p. 33, f. 429-432, 1887. 



This form lies between the groups of candidissima and otthiana. 

 It cannot be united with the former on account of the form of the 

 apex. It differs from spiranomala in lacking an umbilical angle, 

 and in having the whorls much less closely united at the sutures ; it 

 differs from thayaca and titanodolena in having the whorl much 

 more deeply deflexed at the aperture. The species is probably con- 

 fined to the basin of the Isser, and seems to be widely distributed 

 therein. 



Unfigured Leucochroce. 



L. ADANENSIS Naegele, Nachr.-Bl. D. M. Ges. 1890, p. 140. 

 Adana, Cilicia, Syria. Resembles fimbriata Bgt., but is more 

 depressed, the umbilicus is constant though more or less covered; 

 the keel is not crenulated, and the size is larger alt. 8-10, diam. 

 16-18 mill. 



Genus LAOMA (vol. Ill, p. 68, -f- Phrixgnathus, III, p. 37). 

 Laoma (Gray) PILS., Nautilus, Sept. 5, 1892, p. 55. 



L. MARINA Hutton. PI. 23, figs. 17-20. 



Shell small, trochiform, carinated, narrowly perforated ; thin ; 

 subtransluceut, corneous, closely striped with reddish undulating or 



