the Cyclostomacea of Eastern Asia. 457 
this one portion of the shell is sufficient for a division of the 
genus. 
The section Dioryzx, however, as proposed (provided the de- 
pressly turbinate and strongly sculptured species A. crenulatus 
be omitted) consists of a very natural and well-marked group of 
forms, all of a somewhat globose shape, with a short sudden 
constriction close to the peristome, and smooth (or, at the most, 
striated), while nearly all other species are more or less strongly 
costulated, at the inflated portion of the last whorl. There may 
perhaps be some slight affinity between these peculiar globose 
forms and the tubulated genera of the Pupinine, especially 
Raphaulus. 
The subgenus Dioryz, as thus defined and restricted, embraces 
the following species :— 
A. amphora, Bens. Molmain, Burma. 
A. urnula, Bens. Darjiling, Sikkim. 
A. distortus, Haines. Siam and Cambodia, Himalayas. 
?A. pilula, Gould. Hong-Kong, China; 
and a fifth species from Cambodia, obtained by M. Mouhot, of 
which I have not learned the name. 
It will be observed that this group prevails to the eastward, 
only one solitary representative being found on the Himalayas, 
Doubtless other species, in considerable numbers, of all sections 
of the genus Alyceus may yet be found in the unexplored Malay 
and Chinese countries and in some of the large islands of the 
archipelago*, 
The description of A. pilula is very imperfect, and I have never 
seen the species; but it may possibly belong to Dioryz, as no 
transverse sculpture is mentioned as occurring on the whorls. 
The spiral striation is peculiar. 
The remaining species of Alyceus are, for the most part, very 
difficult to distmmguish by any one special character, though they 
may easily be grouped round different typical species. In this 
way we may obtain seven more or less well-marked sections, 
which may be briefly described. 
I. Type, A. gibbus, Fér. Shell perforated, subpyramidal ; 
constriction remote from the aperture; sculpture fine; sutural 
tube elongated. 
A, gibbus, Fér. Cochin China. 
A. pyramidalis, Bens. Tenasserim, Burma. 
* The great proportion of large shells to small amongst the species 
described from the Philippine Islands, and the different ratio found else- 
_ where, where the minute forms have been carefully sought for, renders it 
probable that the Molluscan land-fauna even of those islands has only as 
Ann. & Mag. N. Hist. Ser. 3. Vol. xiii. 30 
