628 REPTILIA 
extend a little farther back than the level of the cloaca. 
Each is furnished with a very short ureter. In the male the 
ureters unite with the vasa deferentia; in the female they 
open separately into the cloaca. Into the cloaca opens also 
a large thin-walled “urinary bladder”; this is a remnant of 
the foetal allantois, and has no functional connection with 
excretion. The urine is semi-solid, and consists largely of 
uric acid. 
Reproductive system.—In the male the testes are two 
white oval bodies suspended in a dorsal fold of mesentery. 
Along the inner surface of each runs the epididymis, which 
receives the vasa efferentia, and is continuous posteriorly 
with the vas deferens. The two vasa deferentia, after 
receiving the ureters, open by small papillee into the cloaca. 
In connection with the cloaca there is a pair of eversible_ 
copulatory organs, postero-lateral in position. 
In the female the ovaries occupy a similar position to 
that of the testes in the male. The oviducts open far 
forward by wide ciliated funnels; as they pass backward 
they show a gradual increase in cross-section, but there is 
no line of demarcation between oviducal and uterine 
portions. Posteriorly, the oviducts open into the cloaca. 
The right reproductive organ (ends to be larger and in front of the 
left. In many of the males the Wolffian body is well developed. 
Viviparous, or what is clumsily called ovo-viviparous, parturition is 
well illustrated by Lacerta vivipara, Anguts fragilis, Seps, etc., but 
most lay eggs with more or less calcareous shells. In Zrachydosaurus 
and Cyc/odus the embryo seems to absorb food from the wall of the 
uterus. It is likely that Lacertilians existed in Permian ages, but their 
remains are not numerous before the Tertiary strata. 
Many instructive illustrations of evolutionary change are afforded by 
lizards. Thus there are numerous gradations in the reduction of the 
limbs, from a decrease in the toes to entire absence of limbs. The 
diverse forms of tongue and the varied positions of the teeth are also 
connected by gradations. From the variations of the wall-lizard 
(Lacerta muralis), Eimer elaborated most of his theory of evolution. 
Some Families of Lacertilia 
In the Geckos (Geckonidze) the vertebrze are biconcave or amphi- 
ccelous, the tongue is short and fleshy, the eyelids are rudimentary, the 
tecth are pleurodont, the toes bear numerous plaits, by means of which 
they adhere to smooth surfaces, e.g. Platydactylus. : 
