ARCHEGOCOPTIS. 301 



nuclear and about a dozen subsequent whorls ; those following 

 the nucleus are rather strongly obliquely ribbed with close set 

 fine riblets which become fainter over the main body of the 

 spire and reappear again on the last whorl; aperture entire, 

 simple, rounded, but a little angular at the posterior outer 

 corner; the umbilicus closed, the spire gradually enlarging to 

 the eleventh whorl, then slightly attenuated. Alt. 12.5, max. 

 Liam. .32 mm." (Doll). 



New Mexico: In the debris of the Rio Grande at Mesilla 

 ;T. D. A. Cockerell). 



Holospira (Haplostemma) cockerelli DALL, Nautilus, xi, 

 62 (Oct., 1897). 



' ' This is the second species of Haplostemma, and one of the 

 tallest, if not the smallest, Holospira yet recorded. ' ' 

 HOLOSPIRA ROEMERI (p. 97), var. minor STERKI, Nautilus, 

 p. 6 (nude name). COCKERELL, Nautilus, xi, p. 136 (last 

 >ur lines), based upon var. b BINNEY, Man. Amer. Land 

 iclls, p. 422 (" Smaller, more ventricose above; whorls 12, 

 le last more briefly loosened; length 11, diam. above the 

 addle 4 mm."). This form is merely an individual vari- 

 tion. 



Genus ARCHEGOCOPTIS Pilsbry, 1903. 

 Shell pillar-shaped, broadly truncate, with a flattened, 

 ieply-sloping plug, and six to ten whorls in adults; the 

 imputated early portion of the spire long and many-whorled, 

 ttenuate; protoconch of nearly 4 whorls, the first one high, 

 irned down and smooth at the apex, elsewhere sculptured 

 dth irregularly-spaced vertical riblets; following whorls 

 dth groups of short riblets below the suture (pi. 41, fig. 69). 

 Surface of the post-nepionic shell lusterless, densely sculp- 

 ired with fine, waved, irregular striae (pi. 41, fig. 70). 

 lorls flattened, the last carinate below, shortly free in front. 

 Lperture subcircular, the peristome continuous. Axis slen- 

 ler and straight, imperforate. 



Jaw arcuate, -moderately strong, densely and irregularly 

 iriate vertically, 1.2 mm. long (pi. 63, fig. 46 X 60; fig. 47 X 

 500, A. crenata). 

 Radula wide, of the usual proportions, with 21.1.21 teeth in 



