substantial objection to this supposition, but at the time of development of the animal, 

 the basic chitinous elements of armament are formed, not directly in the cuticle but 

 in the mass of the parenchyma. How to recognize all these significantly contradictory 

 data without special research does not appear clear to us. 1 



1 



During recent years numerous data concerning the structure of the epith- 

 elium of digenetic trematodes and tapeworms were published by Logachev 

 (1953-1955). His works deserve more careful attention. 



Dermal glandular cells which, as was pointed out, are strongly 

 developed in the main are grouped in the anterior and posterior ends of the 

 body. Near the anterior end they are located mainly along the sides of the 

 pharynx and along the buccal aperture, and open outside terminally or sub- 

 terminally. Apparently the head glands of Monogenoidea are homologous to 

 the head glands of the larvae of Gyrocotylidae, Cestodaria, Udonellidae, 

 and also to the frontal glands of turbellarians. The glands of the anterior 

 end of the body are most powerfully developed among Dactylogyrus but they 

 are often also encountered among the remaining monogenetic trematodes, 

 and among the latter they are relatively more strongly developed during p. 43 



the early stages of the life cycle. The overwhelming majority of the dermal 

 glands are of the sticky or glutinous type and to a lesser degree one also 

 encounters the lachrymous type. The presence of poisonous (narcotic?, 

 nobis) dermal glands, characteristic of a number of turbellaria, is pro- 

 bable among monogenetic trematodes, however, we do not have exact data 

 relative to this subject. Besides the dermal glands there are also glandular 

 cells located in the main body of the parenchyma which are of uncertain 

 origin. These are large cells lying for the most part in groups in the pos- 

 terior end of the body and opening to the outside in the attaching disc. To 

 this group are related,, for example, the powerful cells'of the so-called 

 post seminal glands described in detail by Goto and Kikuchi (Goto and 

 Kikuchi, 1917) for Dactylogyrus inversus Goto and Kikuchi, and widely 

 distributed among Dactylogyridae. Excretory ducts of all the dermal 

 glands open on the surface of the body of the animals by unarmed apertures. 



Armature of the cuticle occurs relatively rarely. Among 

 Diplectanidae the cuticle is covered by delicate scales predominantly on 

 the posterior half of the body and also partially on the attaching disc (Fig. 

 56). These little scales have a more or less sharpened front edge which 

 extends freely above the surface, while the more rounded edge lies in the 

 body of the cuticle. Besides that, Rhamnocercinae are armed by real 

 thorns (see page 359). Among a number of Capsalidae there is strong 

 cuticular armament consisting of a varying number of thorns lying mainly 

 along the sides of the dorsal surface of the body. These thorns are located 

 in parallel rows, each consisting of several thorns. The shape of the thorns 



37 



