REMAKKABLE SPECIES OF ECHIUROIDS. à 



111 the preserved state, it measures about 20 mm. in lengtli and 

 10 mm. in maximum breadth. The j^roboscis is long and slender, 

 being in the fully extended state nearly six times as long as 

 the body proper. Anteriorly it splits as usual into two long 

 branches ; ventrally it is somewhat deeply grooved for the entire 

 length. 



The ground-color of the worm is a grayish brown ; over it 

 are scattered numberless small specks of a blackish brown color. 

 These pigment specks are especially dense over the basis and the 

 dorsal surface of the j^roboscis. The skin-papilUe are relatively 

 small and sparse, except in the anterior and posterior parts of 

 the body where they are slightly larger and crowded than in 

 other regions. 



One of the most peculiar features of the species is offered 

 by the ventral hooks. Instead of being present in a single 

 pair as in all other known Bonellia, they are very numerous, 

 there being no less than twenty-nine in all (fig. 6, PI. II.). 

 Moreover, they are so small in size that they might easily 

 be overlooked by the naked eye. They are of an elongate 

 conical shape, gently bent like a horn, and measure commonly 

 0.f")-l.'') mm. in length. Their color is a pale yellow. They 

 are found irregularly scattered in a small area directly behind 

 the oral aperture. Examined from the inside of the body-wall, 

 the bases of the hooks .are seen to be deeply implanted in two 

 cushion-like muscular pads, symmetrically situated one on each 

 side of, and in direct contact with, the ventral nerve-cord (fig. ü, 

 PI. IL). In the pads the inflated bulbs of the hooks appear 

 as double-contoured circles {h.h.). Several branching muscles 

 {r.m.) radiate from the pad periphery, soon to attach themselves 

 to the body- wall. 



