622 
Proceedings of Royal Society of Edinburgh. 
ill. 
'Markings about 4 in ‘01 mm., least crowded to- 
wards centre. Border narrow, 
Markings about 4 in - 01 mm. Border broad, 
sharply defined, striated, .... 
- Markings towards centre 3^, towards border 4|, 
in *01 mm. ; smaller round granules at intervals 
among the larger ; rows inconspicuous, monili- 
form at border, interspaces narrow, 
L Markings otherwise, ...... 
galapagensis. 
gemvnatulus. 
pauper. 
112 . 
f Markings granular; about semiradius 6, at border 
) 8 to 9, in ‘01 mm.; rows radial, secondary rows 
distinct only beyond semiradius. Central 
space circular. No rosette, . . . . decussatus. 
I No such secondary rows, . . . . . 113. 
( Surface with an elongated somewhat curved de- 
j pression on each side of valve, about § of 
1 radius from centre. Rows radial, . . . biplicatus. 
I No such depressions, 114. 
f Markings obtusely angular, robust, subpearly, 4 
in ’01 mm. ; rows radial, alternately longer 
I and shorter, spaces at origin of shorter rows 
114. ^ hyaline, ....... 
| Markings delicate, granular, rounded, 5 in 
j '01 mm.; rows radial, interspaces wide, 
l No such wide interspaces, .... 
115 / Markings obviously punctate, . 
* \ Markings not obviously punctate, 
biradiatus. 
apollinis. 
115. 
• 116. 
117. 
{ Border broad, of two parts, inner striated, outer 
| hyaline, Weyprechtii. 
116.4 Border simple. Markings robust, 3| to 4, in- 
creasing outwards to 2\ or 3, in '01 mm.; 
I central dots prominent. A rosette, . . asterornphalus. 
. , m / Markings in contact and angular throughout, . 
' \ Markings not in contact and angular throughout, 
118. 4 
'Markings towards centre 3, increasing outwards 
to 2 at border, 5 in *01 mm. ; secondary oblique 
rows not conspicuous, 
Markings more delicate, towards centre 3J, in- 
creasing outwards to 2| on an angular some- 
what elevated zone, at border 6 or 7 in ‘01 mm. ; 
radial rows indistinct, ..... 
Markings towards centre 4, at § radius 3 in *01 
mm., thence rapidly decreasing to border ; 
radial rows distinct, secondary rows incon- 
_ spicuous, ....... 
f Markings rounded, sometimes angular, towards 
| centre 6, increasing slightly outwards, at border 
| 6 to 8 in "01 mm. ; central papillse prominent, 
119.4 rows radial, ....... 
I Markings towards central space rounded 4, soon 
becoming hexagonal and gradually increasing 
l outwards to If or 2 in ’01 mm. near border, . 
f Adjacent to border a distinct band, with mark- 
ings well-defined, elsewhere outlines of mark- 
102. -{ ings faint. Markings 3^ to 4 in - 01 mm., 
increasing but little outwards, 
l No such band adjacent to border, 
118. 
119. 
crassus. 
heteroporus. 
boliviensis. 
apiculatus. 
gigas. 
Janischii. 
120 . 
