STRUCTURE AND DEVELOPMENT OF LOXOSOMA. 321 
Loxosoma. The tentacles of Argiope are formed from the 
dorsal lobe of the mantle. The Brachiopod larva is stated not 
to possess the head-kidney so characteristic of ordinary Tro- 
chospheres. 1 
Shipley (41) after pointing out the importance of the 
absence of the head-kidney in Brachiopoda, has come to the 
conclusion that there is no close relationship between these 
animals and the Polyzoa, and further that they are not 
nearly allied to P boron is. My observations do not warrant 
me in criticising Caldwell’s statements on this head, although 
it does not appear to me improbable that the similarities 
between Brachiopoda and Phoronis may be superficial. 
The position of the cephalic segment with the eyes inside the 
mantle cavity during the metamorphosis of Argiope, seems, 
however, to render Caldwell’s view that the prseoral lobe in 
Brachiopoda persists in part as the epistome, as in Pho- 
ronis, not impossible. 
Brooks’ observations (16) on Lingula probably show that 
the larvae of this form are more easily reducible to the 
Trochosphere type than those of the hinged Brachiopods. 
It appears to me that the curvature of the alimentary canal of 
Lingula is the same as that of a Trochosphere, and 
consequently directed in the opposite direction to that of 
Phoronis. It is hardly necessary to criticise Brooks’ remarks 
on the similarity between the larvae of Brachiopoda and 
Loxosoma, based, as they are, on what I regard as an entirely 
mistaken view (due to Barrois) of the archetype from which 
the Polyzoan larvae are derivable. 
One of the main difficulties in the comparison between the 
Polyzoa and other forms is the great uncertainty of the rela- 
tionships of the Polyzoa inter se. Lankester (45) has adopted 
the view that Rhabdopleura and the Phylactolaemata are 
allied to Phoronis and consequently are more archaic than 
the Entoprocta; the main reason for this view is their posses- 
sion of a body cavity, a structure certainly not present in the 
Entoprocta in the same form. From the researches of 
1 This statement probably requires further proof. 
