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A. INGRAM AND J. W. S. MACFIE. 



them, but dorsally it is open to accommodate the saw-like element to be referred to 

 immediately. The lateral chitinous lamellae extend to the tip of the siphon, where 

 they come into relationship with the ends of the internal structures, and they bear 

 at their extremities two pairs of slightly chitinised hooks. At the base of each 

 lamella there is a single bristle, which lies therefore at about the same level as the 



Fig. 1. Siphon of Mansonioides africanus; (1) outer case, lateral 

 view; (2) apical third of the outer case, ventral view; (3) inner 

 elements : Tr, trachea, S, saw, L, the lateral pieces, V, ventral pieces, 

 Ax, axial rod; (4) ventral pieces flattened out and seen from the 

 ventral aspect: L, the lateral x>ieces in profile; (5) saw flattened out, 



dorsal view. 



larger dorsal bristles, but more ventrally and not as figured by Edwards. These 

 bristles are simple and are not furnished with a fringe or membrane. The ventral 

 membrane is feebly chitinised and is irregularly ribbed or folded transversely, so 

 that in profile it looks like the edge of a file. It is attached laterally and basally 

 to the chitinous part of the siphon by a delicate membrane. 



