ART. 23 FEESH-WATEE MUSSELS, ANODONTITES MARSHALL 5 



the European species for type, all Anodontas would now be A/to- 

 dontites. The reason he selected the South American shell may have 

 been that coming from such a distance it excited a pecuiiar interest, 

 which the home species had failed to arouse because of his familiar- 

 ity with them, and also that he saw that the South American shell 

 was of a species that had never before been found and its sculpture 

 of a delicacy and beauty that until then were unknown in fresh- 

 water mussels and that rarely have been equaled in species discov- 

 ered since. Marshall (1930(2, p. 128) published a brief note on this 

 style of sculpture in Anodonf'/fcs and other genera, remarking that 

 so far as known to him it is found only in naiades from the region 

 which includes the northern edge of South America, Honduras, and 

 Nicaragua. 



Lamarck (1799, p. ST) described the genus Anodonfa as follov>^s: 

 "Anodonte. Anodonfa. Shell transverse having three muscular im- 

 pressions, hinge simple, without any tooth. Mytilvs cygnetis L." 

 There is nothing here to differentiate Anodonta from Anodontifes 

 except the citation of Myt'dus cygneus Linnaeus as an example of 

 the new genus. It seems probable that Lamarck intended Anodonta 

 to replace Anodoyitites.. though it is impossible to think of any just 

 grounds for the substitution. It is to be noticed that Lamarck's 

 description says nothing about the sinulus. 



Lamarck (1819, p. 83) gave a much longer description of Anodonta 

 than he gave originally (1799, p. 87). His description and remarks 

 indicate that he, too, considered the anterior end the posterior. He 

 says: "But what especially distinguishes them {Anodonta) is that 

 here the cardinal tooth and the lateral tooth of the Mulettes {Unio) 

 have entirelj'^ disappeared and that the hinge offers only a simple 

 border adnate or applied under the nymphe which is terminate-! 

 anteriorly by a truncation or sinus. It is in this sinus or in the little 

 space which the truncation leaves that the anterior extremity of 

 the ligament buries itself." The sinus spoken of here is what we 

 now call the sinulus or ligamental scar in each valve at the posterior 

 (not anterior) end of the ligament. 



While, according to our idea, Bruguiere and Lamarck both had 

 their shells " wrong end to," yet Lamarck had the correct idea of the- 

 posterior end of the animal, which occupies the shell. He says 

 (1819, p. 84) : " The animal of Anodonta has two short tubiform 

 apertures, which it forms with the posterior extremity of its mantle 

 and which are furnished with small tentacular filaments." Doubt- 

 less Lamarck, great naturalist though he was, would have enjoyed 

 the joke he perpetrated on himself had he noticed the absurdity of 

 having the rear end of the animal at the " front " end of its shell. 

 It may be that other naturalists of his day had not sufficient knowl- 

 edge of shell and animal to note the absurdity. At least there seems 



