— u 
My renewed study of Temmocephala haying resulted in the discovery of eilia 
on the surface of certain of the species, and having led to the conelusion that “Stäb- 
chen” exaetly, like those of Rhabdocoele Turbellarians are present in abundance, the 
line of demarcation seems still harder to draw. 
The integument of ZTemmnocephala is quite exceptional if we are to regard that 
genus as an ectoparasitic Trematode. A complete distinet epithelial layer does not 
oceur in other genera, though in some (MViischia and Zpibdella) as observed by Braun,') 
such a layer is distinguishable on some parts of the surface — but without cutiele 
or basement-membrane. In the others the outermost layer of the body seems rather 
to correspond to the basement-membrane integument of Temnocephala than to a modified 
epidermis; it is homogeneous, does not readily become stained, and seems to be of 
a resistent character. On the other hand in this regard 7emnocephala approaches 
very near to the Rhabdocoele Turbellaria; the epidermal layer is of similar character 
in the two groups, and the presence of cilia in two of the species of Temmocephala 
makes the resemblanee very elose. The basement-membrane is absent in the Ahaö- 
docoela, but it would not appear to be present in all the species of Temmocephala (see 
Weber’s account of 7. Sernperi quoted above). Tactile cones similar to those of the 
integument of Zermmocephala have only been found elsewhere, so far as I am aware, 
in a Trematode (Sphyranura’); but the delicate motionless hairs that oceur among the 
vibratil eilia in the Rhabdocoeles are of a similar nature. 
A striking point of resemblance between the Temnocephaleae and the Arkahdo- 
coela is the presence in both of the system of unicellular integumentary glands for- 
ming rhabdites (Stäbchen). "The arrangement of their duets in the former as they 
run forwards in the anterior region of the body into broad strands or “Stäbehen- 
strassen” preeisely eorresponds to what we observe in many Rhabdocoeles; and nothing 
of the kind appears to occur among the "T’rematodes. 
The structure of the pharynx is simular to what obtains in some of the Rhab- 
doeoeles such as MHesostomum; but, on the other hand, it appears to be equally near 
to that of the corresponding organ in Polystomum, Sphyranura, and certain other 
Monogenaca. 'he intestine and its epithelium closely resemble those of a Rhabdo- 
coele — the only difference of importance being the presence of construetions in most 
species of Zemnocephala. 
!) Tom. eit. p. 422. 
2) Wright and Macallum, Sphyranura Osleri, a contribution to American Helminthology, Journal 
of Morphology, Vol. I. (1887.) 
