146 WILLIAM BLAXLAND BENHAM. 
body to the anal ring; 3. The invaginated foot.” It appears 
to me more reasonable to consider the region around the anus, 
enclosed by the perianal ring of cilia, as the third division, 
and to regard all that part of the body between the two bands 
of cilia, together with evaginated foot, as the second division. 
But in either case, his comparison of what happens in Phoronis 
and Brachiopoda, will not hold, for in Terebratulina (see 
Morse, 20) the “peduncular” segment elongates rather than 
evaginates. Moreover, it is not the middle segment but the 
terminal one. As to the relation of the dorsal and ventral shells 
of Brachiopoda, Shipley (24, p. 516) has shown that Caldwell 
has no grounds for his assertion that both shells are ‘‘ ventral.” 
The relation which he sees between the nephridial funnel 
and duct to the mesentery is, as I have pointed out above, 
erroneous. The external aperture lies on the wall of the 
rectal chamber, and not of the lateral chamber. 
Certainly the arrangement of the tentacles is somewhat 
similar in Phoronis and in Brachiopoda, and in both the body- 
cavity is divided by a transverse septum into a visceral cavity 
and a tentacular cavity ; but a detailed comparison between 
the adults, and especially between the larve, and the mode of 
development in the two cases, shows no close resemblance 
between Phoronis and Brachiopoda. 
6. Relation of Phoronis to Polyzoa. 
The great resemblance that exists at first sight between 
Phoronis and the Phylactolematous Polyzoa becomes con- 
siderably reduced when a detailed comparison between the 
adults and larvee is made. In both there is the close approxima- 
tion between mouth and anus, the former being overhung by 
a fold or lobe known as the “ epistome.”’? The tentacles, too, 
are arranged somewhat similarly in the two cases, and there are 
other points of resemblance ; but, as Harmer (8) has pointed 
out, the differences are of some importance. 
In Phoronis practically the whole body is ventral, whereas 
20 « Kmbryology of Terebratulina,” ‘Mem. Bost. Soc. Nat. Hist.,’ LI. 
