224 INTRODUCTION. 
considerably longer, and in the latter presents several 
large convolutions. In H. intertexta, U. ligera, H. gu- 
laris, and H. suppressa, it is mucli shorter. Generally, 
it is a white, narrow, cylindrical, frequently undulated 
tube. Sometimes it is distinctly and strongly muscular, 
as in H. albolabris, II. tridentata, II. elevata, etc. In 
H. faliginosa its lower part is dilated to the diameter of 
the penis, and is strongly muscular. In H. albolabris, 
H. tridentata, and H. exoleta, at its commencement it 
presents a dilated and glandular appearance. In H. 
solitaria it is much dilated, t annulated, and glandular at 
its termination. In all instances except in H. eellaria 
and H. alternata, it joins the summit of the penis ; in 
the two latter it joins the penis at the side, very near 
the summit. 
The penis varies very much in form and size ; most 
usually it partakes of a conico-cylindroid form. In H. 
sayi, H. texasiana, H. inflecta, and II. auriculata, it 
is very large and long, cylindrical, collapsed, and flaccid. 
In H. concava it is long, clavate, and bipartite at the 
summit. In H. alternata, H. pterspectiva, and H. solita- 
ria, it is short, stout, and clavate. In H. albolabris, H. 
tridentata, H. multilineata, U. arborea, H. dentifera, 
and H. palliata, it has a thick, preputial membrane, 
originating around its base, and rising upwards so as to 
envelop it for one or two-thirds of its extent. In H. pro- 
funda the base of the penis protrudes into a sheath join- 
ing the cloaca, in the form of a cone with its apex bent 
upon itself. In //. lit/era, H. intertexta, and H. sup- 
