1460 MVCH'I'OPODA 



Var. staudingeri (von Ihering). 



More decidedly obliquely truncate behind and more nearly 

 straight on the base than typical siliqiiosa. 



Upper Amazon in Ecuador and Peru. 

 Mycetopus staudingeri von Ihering, Arch, fiir Naturg.. 1890, 



p. 131, figs. A, B. 

 Mycetopoda staudingeri Simpson, Syn., 1900, p. 934. — von 



Ihering, Abh. Senckenb. Ges., XXXII, 1910, p. 121. 



Von Ihering. (1. c. 1910, p. 121), says in regard to this 

 form : "The strong elevation of the dorsal margin, especially 

 behind the sinulus, as well as the post-sinual posterior adduc- 

 tor scars, are characteristic of this species. It is restricted in 

 its distribution to the region of the Upper Amazon, whence I 

 have it from Iluallaga and Huagamba. The specimen "B," 

 which I figured, has a length of 103 and a diameter of 21 mm. 

 The height in the middle of the shell is 36 and at the posterior 

 angle of the dorsal margin 43 mm. 



The variety from Ecuador, which I mentioned in mv orig- 

 inal description, (p. 130), is decidedly larger. It reaches a 

 length of 142 mm., but the largest specimen that I have ex- 

 amined is apparently, judging from the muscular impressions, 

 not fully grown. Moreover this Ecuador form has the anterior 

 end lower and the posterior end much more elongate ; I, there- 

 fore, distinguish it as var. (equitorialis var. n. It was cited 

 by Clessin, Mai. Bl., N. F., I, 1879, P- 174- from Ecuador as 

 M. siliquosiis Orb. from specimens collected by Higgins." 



Mycetopoda orhignyi von Ihering. 



"Of this species, which d"( )rbigny confused with M. sil- 

 iquosa, I have examined a specimen from Ijolivia received 

 from d'Orbigny. I have scarcely anything to add to the de- 

 scription and figure of d'Orbigny, except that the position of 

 the posterior muscular impressions is prajsinual. This species 

 differs from M. siliqiiosa in its considerable size and much 

 longer posterior region. The latter does not really exceed 80 

 mm. in length and has the anterior end much smaller than this 

 s])ccies. The adductor scar is decidedly pnesinual. ( h^ the 



