178 THE CHICAGO ACADEMY OF SCIENCES. 



Distribution: Europe and America. 



KEY TO SPECIES OF VITREA. 



A. Shell large, exceeding 10 mill, in diameter; widely umbili- 



cated; aperture much expanded draparnaldi 



B. Shell small, less than 10 mill, in diameter. 



a. Shell umbilicated hammonis 



b. Shell imperforate, but indented about the umbilical re- 



gion indentata 



66. Vitrea draparnaldi Beck, pi. xxviii, fig. 5. 



Helix draparnaldi RECK, Index Moll., p. 6,. 1837. 



Shell: Of good size, depressed, thin, but solid when adult, 

 pellucid, umbilicated;surfacesmooth, polished, shining, marked 

 by numerous very fine, oblique lines of growth; color greenish- 

 horn, sometimes lighter; periphery rounded; sutures very de eply 

 impressed; whorls five to fiveand one-half,rounded, convex very 

 regularly increasing, the upper surface flatly convex; aperture 

 a little oblique, transverse, not dilated, the transverse diameter 

 much longer than the height; peristome simple, thickened, ter- 

 minations widely separated; umbilicus round, broad, deep, ex- 

 hibiting a few of the volutions; base of shell rounded, thick- 

 ened within by a deposit of bluish-white testaceous matter. 

 Greater diam., 15.50; lesser, 13.00; height, 8.00; umbilicus diam., 2.75 mill. 



(10108.) 



Greater diam., 7.00; lesser, 5.75; height, 3.00; umbilicus diam., 1.50 mill. 

 (10148.) 



Animal: With a long, narrow foot, long and slender eye- 

 peduncles, and short tentacles; color slaty-blue, indigo-blue or 

 blackish above, darker on head, eye-peduncles and neck; collar 

 greenish; animal much lighter beneath; a locomotive disk pres- 

 ent and pedal grooves meeting above the tail, much as de- 

 scribed in V.fuliginosa. Heart situated as in Zonitoidesarboreus, 

 pulsations regular, numbering as follows: 46, 51, 52, 57, 61, 71, 

 84. In some specimens the beats were quite irregular and 

 may be represented by the following diagram (Fig 34) in which 

 the dash represents the interval between each heart-beat: 



FIG. 34. 

 Diagram showing heart-beats of VITREA DRAPARNALDI Beck. 



The smallest number of beats is when the animal is con- 

 tracted, and the largest when extended. Length of foot 25.50 

 mill., width 3.00 when fully extended. 



