324 
POPULAR SCIENCE REVIEW. 
ZOOLOGY. 
A New Larval Cestoid Worm. — In a paper read before the French 
Academy of Sciences (‘* Comptes rendus,” May 14, 1877), M. A. Yillot 
describes a most interesting larval parasite belonging to the group of Ces- 
toid worms. One of the most remarkable things in connexioD with it is 
the nature of its host, which is a Myriopod, the Glomens limbatus , Lat. ; 
the Cestoid worms in all stages being generally parasitic on vertebrate 
animals. 
In its simplest stage it forms little separate cysts, lodged within the biliary 
vessels. These cysts, which are about 0-028 mm. in diameter, might easily 
be mistaken for Gregarina- cysts. They are composed of two transparent 
membranes, and contain two kinds of corpuscles — pale granulations of 
protoplasmic nature, and very refractive yellowish concretions, such as occur 
in all Cestoids. Each cyst can reproduce by gemmation after the fashion of a 
•cell, and in this way these vesicles at last completely fill up the lumen of the 
vessel, forming milk-white masses, visible to the naked eye. The cysts 
then escape from the vessel into the body cavity, by traversing the wall of 
the former, to which they generally remain adherent by a pedicle. The 
multiplication still continues, so that the vessel is soon covered with innu- 
merable cysts of different sizes, but all united by peduncles, and forming 
bunches, often of considerable size, and of a pearly-white colour. 
The vesicles, which are now ovoid, have greatly increased in size, measur- 
ing 0T60 mm. in length by 0T40 mm. in breadth. Their envelope has also 
become thickened ; its outer membrane is composed of transverse and longi- 
tudinal elastic fibres, forming two distinct layers ; and its inner membrane 
exhibits the ordinary cells of connective tissue. At the anterior pole of the 
cyst there is a deep funnel-like depression, which is imperforate, and con- 
sists solely of a conical invagination of the two membranes. In the interior 
of the cyst there is a fine, perfectly recognizable scolex with four discs, a 
stout proboscis, and a simple circlet of fourteen hooks. These are 0-026 
mm. long and 0*080 mm. broad at the process, which is remarkably de- 
veloped. 
From this description of the scolex there would appear to be no doubt as 
to the Cestoid nature of this parasite upon Glomeris , but so far as we remem- 
ber the mode of development described is perfectly unique among the Cestoid 
worms. M. Yillot, indeed, says that in its structure and encystation it much 
resembles the Echinococci ; but at the same time he fully recognizes the 
great differences which separate it from those larval forms, and notices them 
as follows : — u In the true Echinococci,” he says, “ the acephalocyst takes 
no part in the budding, while in the Echinococci of Glomeris the budding 
affects the whole of the cyst and its contents. Hence, in the former case 
the budding is internal ; whilst in the latter it is external. This essential 
difference in the mode of proliferation ” he regards as necessitating the 
formation of a distinct genus, and he proposes to name the new parasite 
Staphylocystis biliar ius, in allusion to the racemose arrangement of the cysts, 
and the connexion of the parasite with the biliary ducts. It is much to be 
