276 



EDWARD S. MORSE. 



details for fear some systematist will instantly announce a new 

 genus or family. Nevertheless, no figure nor description of 

 Solenomya yet published has shown anything approaching these 

 remarkable processes. The unpaired dorsal tentacle is short in 

 .S. togata (Fig. 18), even shorter in 5. velum (Fig. 19), while in 

 I his form (Fig. 17) it is exceedingly large with a broad base. The 



FIG. 17. Solenomya sp.? Annisquam. 



FIG. 1 8. Solenomya togata. 



FIG. 19. Solenomya velum. 



pedal opening shows the same tentacles starting from the pos- 

 terior end of the opening. The same alternate movements of 

 the siphonal opening were observed. The shell as before re- 

 marked differed in no respect from that of S. velum, and I am 

 puzzled at the remarkable difference in structure of the siphonal 

 opening. The question arises whether the Annisquam form 

 may not be the young of 5. borealis. This can only be decided 

 by securing a living specimen of this rare form. 



Professor Drew, 5 in his observations on the habits, anatomy 

 and embryology of members of the Protobranchia, alludes to 

 the great diversity in structure and concludes that the proto- 

 branchia have been derived from a primitive type. The re- 

 semblance he finds in certain stages of the embryo of Yoldia and 



