NO. 3 HARTMAN : ORBINIIDAE, APISTOBRANCHIDAE, PARAONIDAE 223 



and PROTOARICIINAE. Abdominal neuropodia are long and cylin- 

 drical in Orbinia, Phylo and Califia', they are shorter and somewhat 

 compressed in Scoloplos, Haploscoloplos and Scolaricia; they are short 

 and blunt in Naineris and PROTOARICIINAE. Abdominal noto- 

 podia are widely separated middorsally in Orbiniella, Naineris and 

 Califia', they are increasingly nearer together in Scoloplos, Phylo and 

 Orbinia. 



The most significant diagnostic characters are 1) the approximate 

 or exact number of thoracic segments, 2) the extent of the transition 

 region and whether it is abrupt or gradual, 3) the nature of the probos- 

 cis, whether epithelial or muscular and the extent of branching, if any, 

 4) the character of the branchiae, if simple or divided, cylindrical, com- 

 pressed or laterally fimbriated, 5) the comparative lengths of postsetal 

 notopodial lobes and branchiae, 6) the presence of ventral pads, if any, 

 and their place of origin, 7) the presence or absence of podial lobes, their 

 distribution and their number at maximum development, 8) the presence 

 or absence of subpodial lobes or ventral cirri, their extent and number 

 at maximum development, 9) the kinds of setae, especially those in 

 thoracic neuropodia, 10) the details of uncini, subuluncini, furcate 

 setae or other modified setae, 11) the presence or absence of interramal 

 cirri, lateral organs or other surface structures such as ciliated ridges, 

 ciliated mounds, nephridial or gonadial pores, 12) the form and number 

 of anal appendages, and 13) the approximate size and proportions of 

 the body. 



The circulatory system has been described for Phylo foetida by 

 Timofeev (1930, pp. 149-180). It consists of longitudinal and trans- 

 verse connectives in complex arrangement. The longitudinal vessels in- 

 clude a dorsal one which connects with a plexus and lacunae [cardiac 

 body] surrounding the alimentary canal. The ventral vessel is unpaired 

 and slightly to right of center; a pair of much smaller paraneural ves- 

 sels accompanies the unpaired one. The transverse connecting vessels 

 are especially well developed in gonadial segments. There is a peri- 

 pheral arch which permits transport of the blood from ventral to dorsal 

 sides of the body, and a visceral arch which carries it in the opposite 

 direction. These arches have ventral and dorsal branches. This author 

 noted the strong development of anastomoses between the branchial and 

 nephridial vessels, especially those which function as gonadial outlets. 

 Parapodial vessels are proportionately weakly developed. The circulatory 

 fluid is red. 



