492 PROCEEDINGS OF THE NATIONAL MUSEUM vol.99 



Genus PROMETOR Fisher 



Prometor Fisher, 1948, p. 857 (type, P. bentkophila Fisher). 



Diagnosis. — Related to Maxmulleria Bock; proboscis long and 

 ribbonlike, truncate, the borders fused at base to form a differentiated 

 funnel or cup leading to mouth ; one pair of anterior nephridia, into 

 the specialized basal portion of which opens the large nephrostome, 

 which is compressed, fan-shaped, and bilabiate; a single common 

 external nephridiopore ; two well-developed setae close together, 

 without a common external bursa into which both can retract; anal 

 vesicles unbranched sacs with a great number of glandular excretory 

 tubules having an apical ciliated funnel ; neurointestinal blood vessel 

 directly connected with dorsal ; longitudinal muscle layer continuous ; 

 only females known ; probably sexual dimorphism with dwarf males. 



Remarks. — This genus differs from Maxmiilleria Bock (1942, p. 22) 

 in the presence of a specialized funnel or cup at the base of proboscis, 

 in having only a single nephridiopore, and in lacking a specialized 

 external bursa into which the two closely placed setae can be retracted. 



The blood system of MaxTnillleria and Prometor is more like that 

 of Thalassema than of the Bonelliidae {AcanthohoneUia and Hamin- 

 gia excepted) . The neurointestinal connects directly with the dorsal 

 vessel, a small ring vessel being present. This, however, is on the 

 intestine at the beginning of siphon, and not at end of foregut, as in 

 Echiurus and Thalassema. 



PROMETOR BENTHOPHILA Fisher 



Plates 33, 34 

 Prometor benthopMla Fisher, 1948, p. 857, figs. 1-5. 



Description. — Body somewhat slender pear-shaped; anterior third 

 of body wall opaque, tough, the skin with fine transverse wrinkles 

 between very numerous low, flat, closely placed glandular elevations. 

 These are of many sizes, the largest about 1 mm. in diameter, of ir- 

 regular contour and the surface is smooth in contrast to the wrinkled 

 skin between. Posterior two-thirds of body thinner, translucent, 

 smooth, and without glands, even around anus. The innermost mus- 

 cular layer is smooth. Length of paratype without proboscis, about 

 110 mm. 



The proboscis is a fleshy ribbon about 55 mm. long (type), the base 

 forming a cup into which the mouth opens, this cup comprising about 

 7 mm. of the total length. Its lining is folded as if considerable con- 

 traction had taken place. In the paratype (pi. 33, fig. 1) the proboscis 

 appears to have been undergoing regeneration. The cup or funnel 

 comprises nearly all the proboscis. The lumen of its constricted basal 

 portion is small and the lining is furrowed longitudinally like a gullet. 



