ECHIUROID FAUNA OF NORTH PACIFIC — FISHER 491 



a multitude of vase-shaped excretory elements; siphon present; 



hind intestine abruptly enlarged Nellobia Fisher, 1946 



el Skin thin, translucent; Thalassema-Uke proboscis present; anal 



vesicles and siphon said to be lacking' Sluiterina Monro, 1927 



6 I Proboscis cleft at tip into 2 short or long lobes. 



\ Two nephridia ; no setae Hamingia Danielssen and Keren, 1880 



c ". One nephridium. 



d \ Setae 2, typical ; dorsal and neurointestiual vessels very indirectly con- 

 nected by capillaries Bonellia Rolando, 1822 



d\ Setae numerous (29) seated in 2 muscular pads from which muscles 

 radiate; dorsal and neurointestiual blood vessels in direct connec- 

 tion*; male large (28.5 mm. long) without setae. 



Acanthobonellia Fisher, 1948 



&'. Proboscis a short truncate snout; see above Nellobia Fisher, 1946 



a *. Nephrostome at extreme distal end of nephridium ; proboscis cleft at tip. 

 6 \ Two nephridia serving as egg receptacles, between which is a small un- 

 paired nephridium with a basal nephrostome. 



Austrobonellia Fisher, 1948 

 6'. One nephridium, the distal end expanded into a large trumpet-shaped 

 nephrostome. 

 o\ Two setae; neurointestiual vessel starting from intestine at a consid- 

 erable distance beyond beginning of siphon ; elements of anal vesicles 



short and stout Bonelliopsis Fisher, 1946 



c'. No setae; neurointestiual vessel spanning proximal end of siphon; 



elements of anal vesicles long and slender Eubonellia Fisher, 1946 



a*. Nephrostome on a short stalk facing laterally near blind distal end of 

 nephridium. 

 6 \ The two nephridia with a small nephrostome laterally near distal end ; a 

 small blind tube, projecting into coelom and opening on ventral body 

 wall between the 2 nephridiopores, containing a degenerate male, grown 

 fast to walls of tubule by its posterior end (it lacks setae and has 2 

 sperm receptacles) ; gonad of female situated on frenula radiating from 

 cloaca ; anal vesicles in form of tubules opening independently into 

 cloaca; 2 setae (plus 2 substitutes). 



Pseudobonellia Johnston and Tiegs, 1919 



6 *. One nephridium ; no setae ; no androecium Ikedella Monro, 1927 



a*. Position of nephrostome unknown; a large median nephridium between 2 

 small ones ; proboscis with 2 short terminal lappets ; alimentary canal short, 

 scarcely over twice length of body ; size very small (12 mm.) ; 2 setae (plus 

 2 substitutes) Archibonellia W. Fischer, 1919 



•Monro (1927, p. 618) bases the genus on the absence in the type, Hamingia sihogae, of 

 siphon and anal vesicles. Sluiter (1902, p. 44, pi. 4, fig. 7) states that the siphon and 

 anal vesicles "seem" to be absent, "was aber nicht ganz sicher ist, da der darm sehr 

 gelltten hat und die Verhaitnisse nicht sicher gestellt werden konnten." His figure shows 

 only a small part of the anterior portion of alimentary canal and nothing of the posterior 

 part of the internal anatomy. The text figure of entire animal indicates a proboscis much 

 like that of Maxmiilleria, but the tip looks as if it had been injured and was starting to 

 regenerate. Sluiterina siiogae was dredged in 4,391 meters, on nearly black mud, in the 

 Banda Sea. 



♦Although Ikeda (1907, p. 4) gives no figures of topographical anatomy, he says, "The 

 posterior end of the esophagus is embraced by the heart, a broad vascular sinus of a trian- 

 gular shape with the apex directed forward. From the basal angles of the heart, there 

 arise two moderately long vessels (commissures) which eventually join the ventral vessel 

 running over the nerve cord." This is the arrangement in Thalassema and Echiurua, and 

 very different from that of Bonellia. 



