E. C. Faust 
259 
part. The oral sucker leads directly into the spherical pharynx, which in turn 
opens into the oesophagus. This organ runs a tortuous course to the anterior 
margin of the acetabulum, where it forks to form two short solid non-functional 
caeca. With the exception of the bladder the entire series of post-acetabular 
structures is undeveloped. The cephalic glands consist of two mucoid baso¬ 
philic and one granular acidophilic cell for each side of the body. These open 
through separate ducts lateral to the stylet (cgd ). 
The excretory system is composed of a transversely compressed bladder, 
with the collecting tubules arising from the antero-lateral angles and an un¬ 
differentiated drainage tubule in the tail. The excretory pore (ep) is the only 
opening of the system which I have observed. The primary collecting tubule 
branches once, giving rise to an anterior and a posterior secondary tubule. 
Each of these drains three capillaries with their respective flame-cells. The 
system is, therefore, exceedingly simple, consisting of the two groups of three 
cells each, expressed as 3 - 4 - 3 and referable to the formula a + /3. This is extremely 
suggestive of the flame-cell grouping for the adult brachycoeliine, Acanthatrium 
nycteridis (Faust, 1919 b : 210-211) which is 3 + 3 + 3 + 3; and, moreover, 
is known to have the formula a 1 + a 11 + /3* + /3 n , with the basic formula 
« + It is highly probable, therefore, that C. styloidea is a larva of the sub-* 
family Brachycoeliinae, in which the same flame-cell components obtain and 
where the complete formula is expressed as 2 a + 2/k 
Finally, this belief is reinforced by an analysis of the digestive system, 
which has short caeca, and by the late development of the genital organs. These 
are substantial data for supporting the thesis that relationships between larval 
and adult trematodes may be predicted with certainty by a careful analysis 
of the excretory system. 
Cercaria diophthalmica nov. spec. 
(Plate XXII, Fig. 14.) 
This cercaria, for which the name Cercaria diophthalmica is proposed, was 
found once in a'l*2 per cent, infection of Viviparus quadratus (Bens.) and in a 1*8 
per cent, infection of V. lecythoides (Bens.) at Changsha in June, 1921. The 
larva is a styleted worm and has a body covered with long, delicate spines 
and an aspinose tail. The body measurement averages 0-135 mm. in length by 
0-055 mm. in width, while the tail length equals 0-1 mm. The anterior end 
of the cercaria is provided with a large oral sucker, 35 /x in diameter, the inner 
dorsal surface of which has an acute stylet, which consists of base, reinforced 
stem and tip. The small ventral sucker is situated in the posterior third of the 
body and measures only 18/x in diameter. The prepharyngeal region within 
the oral pocket is lined with small head glands (pg), which are of a mucoid 
nature and open anteriad through conspicuous ducts ( pgd ). Immediately 
behind the prepharynx is the pharynx, a small spherical sphincter 10 /x in 
section. Behind the pharynx is the oesophagus, a long narrow structure which 
divides to form paired caeca just anterior to the ventral sucker. 
