C. L. Edwards 
287 
e. SuppoRTiNfi Rosettes and Supporting Plates. 
Ventral. 
The supporting rosettes are found in the wall of the sucker near the end-plate. 
The terminations of the central bar are broadly branched nearly at right angles to 
the bar and the spreading branches are often fused to form holes (Figs. 15, 16). 
In some cases terminal twigs from the opposite ends grow together, thus forming 
perforated plates with two especially large central holes (Fig. 14). These are 
the fenestrated, often symmetrically bilateral plates described by Theel, 1886, p. 181. 
f. Association of Form of Ambui.acral Appendages with Types of 
End-plates in the Bivium. 
Type A only occurs once and in a cylindrical appendage. Type B was not 
determinable in 61 (67*8 7o) cases but in the 29 (32"2 7,,) determinable is in 
cylindrical appendages. Tyjie G is in cylindrical appendages in 3 (4"3 "/J, in 
conical 6 (8'7 °/J and was not determinable in 60 (87 /^). Type D was not deter- 
minable in 17 (77"3 but in the 5 (22"7 ' /o) determinable is in conical appendages. 
Type E was not determinable in 4 (50 °/_^) but like Type D when determinable, 
4 cases (50°/^), is in conical appendages. 
g. Association of Suckers with Types of End-plates. 
The one appendage with Type A end-plate has a sucker. With Type B suckers 
are present in 25 (27'8 7o). rudimentary in 1 (ll /o)> absent in 33 (36'7 7o) ^iid 
not determinable in 31 (34-4 7o)- With Type G suckers are present in 4 (5-8 7o), 
absent in 51 (73-9 "/J, and not determinable in 14 (20-3 7J. With Type D suckers 
are absent in 20 (90-9"/^) and not determinable in 2 (91 7o)> with Type E 
present in 1 (12-5 7o)> absent in G (75 7o)^ and not determinable in 1 (12-5 7o)- 
In two appendages without end-plates one has a sucker and one has not. 
When compared with H. jioridana the absence of suckers with Type B is 
especially noticeable, showing, perhaps, that the sucker is lost first and then 
follows the degeneration of the end-plate. 
h. Association of Supporting Rods with Types of End-plates. 
In the one appendage having jf'y^e y1, supporting rods are absent. With Type B 
they are absent in 64 (711 7J and not determinable in 26 (28-9 /J. With 
Type G supporting rods are present in 6 (8-7 7o). absent in 58 (841 /J and not 
determinable in 5 (7-27^ ). With Tyj^e D they are present in 40 (40-9 /J, absent 
in 54 (54-5 7o) and not determinable in 4 (4-5 7o)> and with Type E, present in 
4 (50 7J and absent in 4 (50 "/J. 
