128 WILLIAM BLAXLAND BENHAM. 
nephridiopores. Mr. Caldwell (4) has shown that the very 
small area between the mouth and anus is the true dorsal 
surface which is somewhat depressed, and at the sides of which 
the nephridiopores are placed; the rest of the body, or “ foot” 
of some authors, is ventral. 
In order to see the mouth it is necessary to remove the 
tentacles on the oral side, which here pass uninterruptedly 
from right to left. The mouth is then seen to be a wide 
though compressed funnel-shaped opening, the corners of 
which are continued as grooves, right and left, between the 
tentacles (figs. 5, 7). The lophophoral ridge, as I have 
already remarked, bends inwards on each side of the anal 
region, and longitudinal sections show it to be fused with 
the body throughout its whole length; and though it is here 
more complicated than in the Naples species, yet in neither 
species could it ever attain the position figured for it by 
Allmann (1, p. 156), whose figure conveys an entirely erroneous 
idea of the animal in this and one or two other respects. 
Dyster (6) and Kowalevsky (15), however, who observed the 
living animal, represent the carriage of the tentacles in their 
natural, and only possible position. 
The tentacles spring from the lophophore in a double series, 
an outer and an inner row, leaving a deep groove—the “ lopho-' 
phoral groove’’—between them (fig. 7, /.g.). This groove 
deepens, and slightly widens on the oral side, and is con- 
tinued downwards into the cesophagus, so that we may 
imagine the corners of the mouth to be enormously drawn 
out on each side, then spirally coiled, whilst each lip or edge 
is provided with a number of long delicate tentacles. 
The lophophore varies in shape in the different species, 
for instance, in the Naples species the incurved ends are only 
slightly bent orally, so as to give a “ horse-shoe-shaped” lopho- 
phore (fig. 12), whereas in both Ph. australis and Buskii, 
4 «Preliminary Note on the Structure and Development of Phoronis,” 
‘Proc. Roy. Soc.,’ 1883, vol. xxiv, pp. 871—383. 
! € Monograph of Freshwater Polyzoa,’ p. 55. 
6 «Notes on Ph. hippocrepia,” ‘Trans. Linn. Soc.,’ 1858, 
1 “Structure and Development of Phoronis.” 
