E. C. Faust 
265 
through hollow spine-capped ducts at the sides of the stylet, have also been 
observed. This is definite proof of the combined action of abrasion and chemical 
erosion utilised primitively by the animal to invade the host. 
Yet the cephalic gland is not a unique accompaniment of the stylet, for it 
occurs in the furcocercariae and non-styleted leptocercariae and in the 
echinostome larvae. The study of known species of cercariae has been too 
fragmentary to formulate any broad statement regarding the specificity of 
the cephalic glands in various groups. As far as is now known, their number 
is specific for mammalian schistosome larvae. In the two brachycoeliid larvae, 
C. styloidea (Fig. 12) and C. diophthalmica (Fig. 13), belonging to different 
subfamilies, there are paired clusters of three such cells, differing in intimate 
structure and chemical secretions, but fundamentally the same. It is impossible 
to conceive how these three cephalic glands can be even generically diagnostic 
in this group. 
Ontogenetically the organs of the larva are important in as far as they 
develop into organs functioning in the adult worm; phylogenetically they are 
of significance in as far as they relate the organism to other similar organisms 
in the past; s}^stematically they are of value only in as far as they show by 
inspection the relation of larva and adult. For the last-named purpose 
differentiation within the groups is highly desirable. Thus far, the only two 
systems which have furnished evidence of such unique properties are the 
excretory system and the cephalic glands. All other systems investigated have 
proved too immature, too generally distributed or too ephemeral in their 
nature to be of fundamental importance in relating larvae to adults. 
It seems highly probable that careful study of cercariae will make it 
possible in the near future to relate entire series to adult groups and, what is 
more important, establish natural groups where artificial groups now exist. 
Summary. 
1. Collections of flukes made in several centres in China include 25 species 
of cercariae. 
2. Fourteen of these species are described as new. 
3. Details of the excretory system are presented for six of the species 
described. In two of these instances (echinostome larvae and furcocercariae) 
differentiation within the natural group is demonstrated, while in two other 
larvae, C. styloidea and C. diojohthalmica, proof of relationship and correlation 
with adult groups is established. 
4. C. abbrevicauda shows striking resemblances to the larva described as the 
cercaria of Paragonimus westermanni and may possibly be regarded as identical 
with the larval stage of that worm. Moreover, the host genus is the same. 
5. The stylet organ is shown to be non-specific and the group of the 
“xiphidio-cercariae” to be a composite of several natural families. 
G. No organs of the cercaria save the cephalic glands and flame-cells have 
thus far proved satisfactory for differential diagnosis of the larva. 
