Coe and Kunkel— California Limbless Lizard. 385 
axis of the body and directly internal to the superficial or ventral 
musculature of the anterior portion of the tail. The posterior end 
of the tube is divided into two cup-like terminal sacs (pl. xtv1, fig. 
39, t.p), representing the two*terminal pits of the everted phallus. 
To these terminal sacs is attached directly the large retractor muscle. 
The main portion of the central tube of the phallus is extremely 
irregular in outline, due in part to the presence of the spiral groove 
and in part to the fact that the invagination takes place on the inter- 
nal and median borders of the organ to a much greater extent than 
on the lateral border. , 
In transverse section of the retracted phallus the spiral groove 
appears as a deep slit varying greatly in outline and position at 
different points throughout its length. At its proximal end it con- 
tinues directly into a conspicuous groove which passes along the 
latero-ventral wall of the posterior cloacal chamber, and thus, when 
the phallus is everted in the act of copulation, the genital fluid is 
conveyed from the cloaca to the spiral groove of the phallus and 
thence to the cloaca of the female. 
The ectodermic lining of the retracted adult phallus is, as stated 
above, composed of stratified scaly epithelium continuous with that 
of the outer covering of the body. The superficial scaly cells, how- 
ever, are reduced to one or two inconspicuous layers, so that it closely 
resembles irregularly stratified columnar epithelium. The scaly cells 
are sloughed off from time to time and collect in masses in certain 
portions of the lumen of the retracted phallus, particularly in the 
two terminal sacs, which in some cases are completely filled with 
these discarded scaly cells. 
The tissues of the phallus both in the retracted and in the everted 
condition are permeated with large, irregular, anastomosing blood 
spaces, forming a sort of erectile tissue, which, when distended with 
blood, causes the rigidity of the organ and aids in its eversion. 
The musculature consists of the retractor phalli magnus described 
above as extending from well back in the tail to the very distal end 
of the phallus, where it divides into two portions which are attached 
directly beneath the two terminal sacs or glands; and of a short 
retractor basalis which is attached to the lateral border of the basal 
portion of the phallus. These muscles are similar to those described 
by Unterhéssel (:02) for several reptiles. A third muscle of small 
size—the rectus phalli—connects the basis of the phallus with the 
neighboring muscles of the cloacal aperture. 
From its everted condition it is easy to understand the manner in 
which the retractor muscles cause the invagination or retraction of 
