214 
South African Cercariac 
stubby limbs which reach to the subdistal region of the body. The acetabulum 
lies in the middle third of the body. It measures 43/x in diameter and is very 
muscular. 
The excretory bladder is a conspicuous non-muscular organ with cornua 
extending forward and a median vessel running backward into the distal 
region of the tail. 
The conspicuous flocculent masses from which the larva derives its name 
are not pigment masses at all, but dense creamy semi-opaque vitelline follicles 
which with the most careful treatment remain unstained. Near their posterior 
limits they are connected with the medially lying germ glands by a pair of 
transverse vitelline ducts. The germ masses are found to contain evidences 
of ovary, receptaculum, Laurer’s canal, vagina and seminal ducts. 
The redia in which the cercaria develops is a large sacculate body with a pair 
of so-called feet near the posterior end and a distinct collar anteriorly. The 
oral sphincter is extremely small. The redia is covered with minute spines. 
The cercaria is provided with abundant material for encystment. The 
transfer to the subsequent host probably occurs after the fluke emigrates 
from the mollusk. 
Cercaria 30-acanthostoma nov. spec. 
Host : Physopsis cifricana. 
Habitat: Lyndenham, Natal. 
This cercaria is the fourth echinostome of Cawston’s collection to be 
described. It differs markedly from Cercaria arcuata and C. constricta. While 
it more nearly resembles C. catenata it differs from that species in many 
significant points. 
Cercaria 30-acanthostoma measures 300/z x 130/jl. The tail is slightly longer 
than the body. It measures 41^ at the base and tapers gradually toward 
the tip. The body but not the tail is covered with flat rhomboid scales closely 
appressed to the integument (Fig. 4). There is a circlet of 30 collar spines 
with blunt points and bases deeply inserted in the integument (Fig. 3). The 
oral sucker is inclined ventrad. It measures 38/z in diameter. The acetabulum, 
which lies behind the middle of the body, measures 45 /jl by 54/z. Between the 
oral sucker and the pharynx is a slight prepharyngeal sphincter. Behind the 
pharynx is a long oesophagus which normally forks just in front of the acet¬ 
abulum. The coeca reach to the subdistal region of the bodv, as in most 
echinostome larvae. 
The excretory bladder is large and distended. The pore opens posteriorly. 
A median cornu connects the bladder with the main collecting tubules. The 
latter are somewhat convoluted (Fig. 2). They contain no excretory granules. 
Running backward from the bladder is the main collecting tubule for the 
tail. It bifurcates at the beginning of the distal fourth of that organ each 
fork of which opens externally. This caudal canal corresponds somewhat to 
the similar organ in C. catenata. 
