96 Macteay Memortat Vouome. 
extended, extremely like /7ydve, for which they have been again and again mistaken. 
The body of Zemnocephala is strongly compressed dorso-ventrally, the dorsal surface 
being convex, the ventral flat or concave. The outline, when the animal is looked at 
from above, varies considerably in accordance with the extent to which the body is 
extended or contracted, and differs also to some degree in the different species : it may 
generally be described as oval or pyriform. The anterior end is provided with a series 
of usually five, sometimes four, sometimes six, in one species twelve, highly extensile 
slender tentacles, which are nearly cylindrical, but a little compressed in the dorso- 
ventral direction, tapering distally. In 7. guadricornis, in which there are only four 
of these tentacles, there is in the middle line a short broad flattened lobe with a 
convex anterior border.* In 7. fasczata, T. minor, T. Dendyt, T. Jheringi, T. 
Sempert, and 7. Chilensis there are five equal tentacles; in 7: Move-zealandiet and 
T. comes there are six. Along the lateral border, from the base of the most external 
tentacle backwards, there runs in some of the species a narrow fold.{ On the ventral 
surface close to the posterior end is a single large, circular sucker, which in some 
forms is more, in others less, distinctly radiated. In front of the anterior edge of 
this is a median opening in the form of a small transverse slit—the common genital 
opening. Further forward, on the same surface, some little distance behind the bases 
of the tentacles, is a larger slit-like aperture—the opening of the mouth. On the 
dorsal surface are a pair of eyes, situated near one another, a little in front of the 
transverse plane in which the mouth lies. At the sides, not far from the lateral 
margins, and nearly in the same transverse plane as the eyes, are the small pores 
which form the external openings of the excretory system. 
Though nearly related to 7emnocephala as regards most essential points in its 
internal structure, Craspedella (Pl. xv. fig. 3) differs somewhat in general shape from 
the members of that genus. There are five anterior tentacles similar to those of 
Temnocephala, but with relatively large papille ; and there is a large posterior sucker. 
But the posterior portion of the body is provided in addition with a remarkable 
series of papillose frmges and processes. 
T. fasciata, T. quadricornis, and 7. Nove-zealandie are richly pigmented, 
especially on the dorsal surface. 7. mznor has a pigment-network which gives the 
animal a greyish colour to the naked eye; 7. Semfer7 is only exceptionally pigmented; 
IT. Dendyt, T. comes, and the remainder are devoid of pigment, or possess only a few 
scattered granules. 
* See my former paper quoted above, Pl. xx. fig. 3. 
+ Erroneously stated to be five, /.c. p. 284. 
t Braun (p. 409), misinterpreting my mention of this fold, refers to it as membrane-like appendages, a phrase which 
conveys an exaggerated impression, 
. 
