48 L, HILLIS-COLINVAUX 



fused units may definitely predominate. The participating filaments 

 may be so interlaced that the structure is very difficult to sort out, and 

 the whole may be further complicated by the fused units firmly 

 adhering for a length approximately equal to the diameter of a filament 

 (Hillis, 1959), so that initially one feels that all the filaments are fused 

 together as in pattern one. 



(ii) Variations in the other three categories of nodal filaments. For 

 most species of the first group (filaments fusing into a single unit) nodal 

 structure is unequi vocable. The pores associated with this pattern of 

 filaments generally show up well if good longitudinal sections are 

 made. The pores are lined up in adjacent filaments, and all the filaments 

 appear to be involved in the fusion. Diagnosis for such material is 

 straightforward. Occasionally, however, particularly in material of 

 simulans, the pores may be small and relatively inconspicuous (Hillis, 

 1959). And in some specimens the connections between some of the 

 filaments may be delicate and easily broken, giving the impression 

 that the nodal structure is that of two or three large groups. Hillis (1959) 

 reported this for monile. Occasionally, in monile two or three separate 

 bundles of fused filaments occur. 



The fourth group (separate filaments) is essentially uncomplicated, 

 except that the filaments may adhere, usually only slightly, and then 

 have to be gently teased apart without tearing, to establish the 

 absence of fusion. In melanesica a very few filaments may join briefly 

 in pairs. 



The fifth category (a single filament) is straightforward. 



(d) Pattern of peripheral or primary utricles. Useful characters are: 



diameter in surface view ; 



surface appearance; 



presence of spines (in scahra) ; 



type and extent of lateral adhesion of adjacent utricles; 



number borne by a single secondary utricle. 



Length of these utricles, although usually given in species descriptions, 

 has not proved useful taxonomically. 



For the first two of the characters surface sections are required ; 

 tor the remainder, longitudinal sections are used. In three species 

 surface characteristics are so outstanding that these microscopic 

 characters may be checked in the field without magnification, or with a 

 X 10 handlens, and the identification subsequently verified in the 

 laboratory. These species are scahra, macrophysa a,nd favulosa. 



