OBSERVATIONS ON LIVING SOLENOMYA. 



279 



are distinct species. It is surprising, however, to see how closely 

 they resemble one another (Fig. 20). At first sight S. borealis 

 seemed to be an enlarged S. velum. The color of the foot and 

 ventral membrane varies. In 6 1 . borealis the foot is a light brown 

 with a tinge of purple, darker on the ventral keel, with a darker 

 blotch near the ventral portion. The papillae on the edge of the 



FIG. 20. Side view of 5. borealis, natural size. 



pedal disk were longer and sharper than in S. velum though the 

 same in number. The tubercles on the edge of the mantle open- 

 ing were the same in number and position, standing out at right 

 angles from the ventral membrane. Their color, like the mem- 

 brane, was brownish, the tips of the tubercles being dark brown. 

 No trace of a white pigment-like color on ventral membrane 



FIG. 21. FIG. 22. 



FIG. 21. Siphonal opening. 



FIG. 22. Anterior end from below: F, foot; P, palp-appendages resting on the 



branchia; B, branchia. 



or tubercles was observed in either young or old. The palpi 

 were not so long though the ends were more foliated (Fig. 22). 

 Their movements were not so active. The palpi rested on the 

 anterior portion of the gills and were evidently engaged in secur- 



