FASCICULI MALAY ENSES 
277 
readily seen that the folding does not merely consist, as Professor Weber 
appears to have thought, of an approximation of the two walls to one another, 
for while the dorsal wall (D) lies back-wards along the dorsal surface of the 
head for some distance, and then curls upwards and outwards at its free 
extremity, the ventral wall (V), which is the longer and stouter of the two, 
runs almost directly upwards at its base, and then curls inwards at its free 
extremity towards the anterior surface of the dorsal wall. It is evident, 
therefore, that the folding of the funnel is due, in the first instance, to a 
bending upwards of the ventral wall, accompanied by a bending backwards 
of the dorsal wall, and that while the free extremity of the former naturally 
curls inwards, that of the latter becomes directed at its tip towards the same 
vertical line from the opposite direction. A very effectual guard to the 
mouth (M) is thus produced, being further elaborated by the arrangement of 
the horny teeth (T) situated on the anterior surface of the funnel. 
The dorsal wall of the funnel takes its origin in the same relative position 
as the upper lip of the tadpole of Rana temporaria. Inferior to it, a small 
horny upper jaw or beak (B), the outline of which is somewhat complicated 
in transverse section, protects the mouth (M), with which I am not concerned ; 
beneath and immediately anterior to it an inconspicuous fleshy ridge (I) possibly 
represents the lower lip, and the ventral wall of the funnel appears as a hyper- 
trophied structure, which may be produced, in its present condition, either by 
the growth round the mouth of the upper lip, or, as seems more probable 
from the mode of disappearance of the funnel, by a general alteration of the 
tissues in this region. The lower jaw, which is very large, is doubled back- 
wards behind the beak, and is not included in the field of the figure, in which 
the posterior half of the upper jaw is also omitted. 
Under a high power it is seen that the bulk of both walls consists of a 
vacuolated central mass, in which it is not possible to distinguish cell 
walls, though nuclei are abundant. The spaces in this central mass are true 
vacuoles, surrounded by anastomosing threads of protoplasm and devoid of 
blood corpuscles ; in life, they appear to be filled with a colourless, amorphous 
jelly, which can be expressed from the funnel if it is violently squeezed. 
Running in the central mass, accompanied by minute capillaries, are a 
number of slender strands of striped muscular tissue, which radiate outwards 
towards the periphery of the funnel. Professor Weber’ figures their course as 
it is seen from above, but represents their ramifications as longer and more 
complicated than my sections would seem to indicate. They are more richly 
distributed in the ventral wall than in the dorsal, and, so far as 1 have been able to 
I. Loc. cit. 
