40 AMPHIDOXA. 



Section AMPHIDOXA Alb. 



Shell small, perforate, depressed-globose, thin and pellucid, costu- 

 late-striate, Whorls 8-82, rapidly enlarging. Aperture ample. 

 Anatomy unknown. Distribution, Juan Fernandez. 

 A. marmorella Pfr. iii, 46. A. helicophantoides Pfr. iii, 46. 



Section STEPHANODA Albers, 1860. 



Stephanoda ALB., Die Hel. (2) p. 88. Type H. dissimilis Orb. 

 Stepsanoda PFR., Nomencl., p. 93. 



Shell umbilicated, thin, costulate, sometimes spirally striated ; in 

 shape like Discus or Charopa. Whorls 5-7, the last cylindrical, not 

 descending. Aperture rounded lunar ; lip thin, simple. Type H. 

 dissimilis Orb., pi. 7, figs. 19, 20, 21. See also pi. 7, figs. 16, 17, 18, 

 A. hookeri Reeve.) 



Anatomy of the typical forms unknown ; of A. hookeri as follows, 

 the living animal according to Eaton's observations (Philos. Trans., 

 1879, p. 183), the internal anatomy according to Schako and Pfeffer 

 (Monatsber. K.-P. Akad. Wissensch. Berlin, 1877, p. 269.) 



Animal (in spirit) with a narrow foot, rather narrower posteriorly 

 than in front. The sole of a pale livid olive, sides dark slate color. 

 Mantle above the head pale livid, dotted with dark slate spots. 

 During life the animal (viewed through a lens), is black, reticulated 

 with gray; tentacles either black above and dark gray beneath 

 longitudinally, or dark gray throughout. Foot bordered above by 

 a ribbon-like stripe which is composed of long oblong tessellations 

 whose interstices are gray, which is separated by a thin pale irreg- 

 ular line from the more finely reticulated upper portion of the sides 

 and back. The interspaces of the reticulation of these last are 

 slightly raised and black, and cause the surface to be somewhat 

 granulated. Some of the lines of growth of the shell are occasion- 

 ally straw color (Eaton). Sole tripartite, divided into areas by two 

 longitudinal and many transverse grooves, the outer areas darkly 

 pigmented. No appendages upon the mantle margin. 



Genitalia simple, without accessory organs ; vas deferens inserted 

 at the apex of penis, passing gradually into it ; spermatheca terminat- 

 ing in a short straight or bent appendage, and situated upon a rather 

 long duct (pi. 1, fig. 16, A. hookeri.} 



Jaw measuring *7 x '68 mill., rather narrow, low-arcuate, sculpt- 

 ured with fine, somewhat wavy transverse striae and numerous nar- 



