106 ASCAROIDEA 



Fam. 12. CHAETOSOMATIDAE Steiner, 1916. 



(Chaetosomatiden Schepotieff, 1908). 



Free-living (marine) forms, usually somewhat swollen in 

 the middle region of the body. Cuticle, except at the ex- 

 tremities, transversely striated. Numerous bristles present, 

 usually arranged in submedian rows. Lateral organs present, 

 circular, horseshoe-shaped or spiral. On the ventral surface 

 in the preanal region, in both sexes, there are two, three or 

 four longitudinal rows of peculiar, tubular or solid, bristle- 

 like " ambulatory " appendages. Lips not distinct. Six 

 circumoral and numerous specialized cephalic bristles present. 

 A small pharynx apparently present. Oesophagus relatively 

 short, muscular, with a posterior bulb and sometimes an 

 anterior sw^eUing or swellings. Male with two slender spicules 

 and usually one or two accessorj' pieces. Male genital tube 

 single, outstretched. Female genital tubes paired, opposed, 

 reflexed. Caudal glands and spinneret present. 



1. Chaetosoma Claparede, 1863. 



Syn. Tristichochaeta Panceri, 1878. 



Cephalic region swollen into an oval .shape, and followed 

 by a narrow " neck." Oesophagus cylindrical, with a posterior 

 bulb. Ventral appendages in two or three rows, tubular, 

 post vulvar in female. 



Hab. Marine. 



Genotype : C. ophiceplicdum Claparede, 1863. 



Claparede, 1863, Beobachtungen iib. Anat. u. Entwick- 

 lungsges. unrbelloser Thiere, etc., Leipzig, 88 ; Panceri, 1878, 

 Atti R. Accad. Sci. NapoU, vii (10), 7 ; Steiner, 1916, Zool. 

 Jahrb., Syst., xxxix, 560; Irwin-Smith, 1918, Proc. Linn. 

 Soc. N.S.W., Sydney, xlii, 757. 



2. Draconema Cobb, 1913. 

 Closely resembles Chaetosoma, but the oesophagus is very 

 short and has one or two anterior swellings in addition to 

 the posterior bulb. Ventral appendages in four rows, with 

 free ends expanded. 



Hab. Marine. 



Genotype : D. cephalatum Cobb, 1913. 



Cobb, 1913, Journ. Washington Acad. Sci., iii, 145; Steiner, 

 1916, Zool. Jahrb., Syst., xxxix, 560. 



The differences between this genus and the last are very 

 slight, and it seems possible that Draconema should be regarded . 

 as a s3Tionym of Chaetosoma. 



