THE DEVELOPMENT OF THE TEl\[NOCEPHALE*E. 421 
IV. The completed Egg. 
The eggs of all the species of Temnocephala, on being 
discharged, are fixed by a chitinoid cement to some part of 
the outer surface of the body of their hosts. In some of the 
species attachment is effected through the intermediation of 
a longer or shorter stalk situated at one end. Such stalked 
eggs occur in T. chilensis according to Monticelli (14), 
Plate (15), and Wacke (16). Similar stalks occur also in 
T. no vaj-zealandise and in T. minor. The cementing 
material usually extends between the stalks of neighbouring 
eggs, thus uniting them into groups as observed by Monticelli 
and by Wacke. In sucli stalked eggs an operculum may be 
formed, when the young animal is ready to become free, by 
the formation of a circular split in the egg-shell near the 
distal end. In both T. novEe-zealandiae and T. minor 
there is a short filament attached near the middle of the distal 
end. T. fasciata, T. comes, T. dendyi, '1'. semperi, and 
T. quadricornis have more or less elliptical eggs which 
have no stalk, but are cemented down by one side, a number 
being, in most cases, united together by means of the cement- 
ing material. Of these the eggs of T. fasciata, T. comes, 
T. quadricornis, T. semperi are provided with filaments, 
those of T. dendyi are devoid of them. 
The size of the egg is, in general, in relation with the size 
of the adult. The larger species — T. fasciata, T. quadri- 
cornis, and T. n o vae-zealan dim — have comparatively 
large eggs, about 5 mm. in length. The minute Craspe- 
della speuceri, at the other extreme, has oval sessile eggs, 
without filaments, which ai’e only 0'2 mm. in diameter. 
Temnocephala, like its allies the Rhabdocoeles and the 
II eter ocoty 1 ea, has no larval stage; the young animal, 
when it escapes from the egg, differing from the adult only 
in its small size, and in the repi’oductive apparatus not having 
attained to complete development. 
