74 THE NAUTILUS. 



soft parts are of more importance than the hard parts of a mollusk 

 in any discussion of generic or other taxonomic considerations. The 

 low features of the protobranchia would never have been suspected 

 from the shell alone. The drawings of the soft parts of the laoielli- 

 branchs, thus far published, are in most instances valueless and mis- 

 leading. An important exception to this statement is the work of 

 Meyer and Mobius. 1 The beautiful drawings of the expanded 

 animals have never been surpassed. The drawings of the soft parts 

 of lamellibranchs in Forbes and Hanley's British Mollueca 1 are, 

 with few exceptions, poor and misleading. In one case, indeed, the 

 siphonal tubes are sticking out of the wrong end of the shell ! As 

 an illustration of the inaccuracy of most of the efforts of drawing the 

 live creature, reference may be made to a drawing of Lsevicardium 

 mortoni, which appeared in Gould and Binney. 3 Where the draw- 

 ing came from I do not know. In no way does it accord with the 

 description of the animal credited to S. Smith, nor does it bear the 

 faintest resemblance to the creature. This cut was reproduced in 

 one of the U. S. Fish Commissioners reports 4 with no comment on 

 its inaccuracy. 



A study of the soft parts of Verrill's genus Gostranella, in a living 

 state, revealed the fact that it was simply an early stage of Petricola 

 pholadiformis, and with this hint I made a complete series of the 

 shell from the extreme young to the adult. Dr. Dall had, however, 

 come independently to the same conclusion regarding the identity of 

 the two forms. With the exception of the classical work of William 

 Clark on the British Marine Testaceous Mollusca the descriptions of 

 the soft parts of mollusca, though rarely given, are usually inade- 

 quate and often incorrect. As an illustration of the character of 

 some of this work, could anything be more absurd than the descrip- 

 tion of the animal of the genus Thracia, which may be found in a 

 standard work on British Mollusca. 8 It embraces a line of four 

 words and is given as a generic distinction, " Body oval, tubes 

 separate." 



In most of the earlier descriptions the siphonal openings of Thracia 

 are described as fringed, and the figures of Thracia phaseolina and 

 distorta in Forbes and Hanley show densely fringed openings. The 

 figures, of course, are entirely wrong, as the descriptions quoted from 

 Clark indicate. The description in Jeffreys of the animal of T, 

 papyracea is the nearest correct of all I have yet encountered : 



