10 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.15 



with difficulty because of the opaqueness of underlying tissues. Also, 

 unless they are removed with the enclosed connective tissue, which is in 

 intimate contact with the tissues below, they are apt to be collapsed or 

 broken. Even in fixed or killed material the inner, soft, membranous 

 portion is often shrunken or collapsed so that the outer sheath is dis- 

 torted. Organs that are heavily chitinized and have articulating bases 

 (see Glycinde) do not present the same difficulties. The beautiful, 

 ornamental symmetry of some of these structures can be seen by com- 

 parison of figures on the accompanying plates. 



The chevrons (pi. 2, fig. 2) which sometimes accompany the pro- 

 boscidial organs, consist of series of V-shaped, flat pieces. It is possible 

 that they function for stabilization of the long body or also to maintain 

 traction during progression. Chevrons are lacking in species of Glycinde, 

 but the series numbered IV (textfig. 2) may be the homologous parts, 

 since they too lack a terminal pore. 



The number of teeth in macrognaths and the number of pieces 

 comprising dorsal and ventral arcs of micrognaths has sometimes been 

 used for specific diagnosis, but it may be doubted if their numbers are 

 as constant as one might wish. Both kinds of paragnaths are probably 

 subject to breakage, loss and repair, and there is apt to be additional 

 variation depending on age or other individual features. More complete 

 details are given in specific accounts. 



The first parapodia are on the first body ring or peristomium. They 

 are small but gradually come to be larger and lateral in position. In 

 anterior segments through a limited region, they are uniramous and 

 consist of a neuropodium with dorsal and ventral cirri. Presetal and 

 postsetal lobes are developed and sometimes have specific significance. 

 Setal structures in notopodia and neuropodia usually consist of single 

 acicula and fanshaped fascicles of composite, spinigerous, or also falci- 

 gerous setae. When transitional segments are present, both notopodia 

 and neuropodia increase in size gradually; this middle region may be 

 very short (a few segments) or long (70 or more segments). Neuro- 

 podia in the posterior region resemble those in front but they increase 

 in size. Notopodia, where present, are much smaller than neuropodia; 

 they have single acicula and few to many simple setae that may be 

 coarse and acicular, or slender to hairlike. 



Presetal lobes of neuropodia are sometimes very characteristic; in 

 species of Goniada they are usually bifurcated; in those of Glycinde the 

 presetal lobe is single but in at least 2 species, G. dorsalis Ehlers and G. 

 armata (Kinberg), there is a partial bifurcation of this lobe in posterior 



