314 HOLARIELLA. 



on the upper part of the next or smaller whorl, besides several finer 

 but irregular ridges on the base of the last or largest whorl, and 

 numerous minute spiral strise between all the ridges ; the principal 

 ridges are placed near the suture of each whorl, both above and 

 below, leaving a broad flattened space in the middle and a narrow 

 excavated space below the suture, thus imparting a tower-like 

 appearance to the shell ; the upper whorls are also marked with 

 numerous short and fine longitudinal ribs, which cross the ridges 

 and make them crenelated ; color pure pearl-white ; spire elevated ; 

 apex semiglobose, prominent and slightly twisted ; whorls 7, 

 gradually increasing in size; suture very distinct; mouth nearly 

 circular, but angulated or somewhat notched below by the um- 

 bilical ridge ; outer lip thin and slightly expanded ; inner lip folded 

 a little back on the umbilicus, and adhering to the pillar ; inside 

 more or less iridescent ; umbilicus large but not wide, funnel-shaped, 

 and completely exposing the whole of the inner spire ; it is encircled 

 outside by a strong spiral ridge, which is often beaded, and winds 

 like a staircase into the interior ; operculum forming a spiral of 

 about a dozen whorls, the edges of which are imbricated and over- 

 lap one another in succession. (Jeff.} 



Alt. 8 diam, 7 mill. ; alt. 7-1, diam. 62 mill. (Jeffreys.) 

 North Sea off Shetland Is., 85-95 fins. ; Gulf of Mexico, Cape 

 Florida to Oiribbees, 193-888 fms. 



Trochus amabilis JEFFREYS, British Conch, iii, p. 300; v. t. 61, 

 f. 6. Solariella amabilis Jeffr. DALL, Blake Gasteropoda, Bull. 

 M. C. Z. xviii, p. 380 (1889). Trochus dnctus Phil. JEFFREYS, 

 P. Z. S. 1883, p. 97. T. affinis JEFFREYS olim T. dnctus var. 

 affinis JEFFREYS, P. Z. S. 1883, p. 98, t. 20, f. 5. Machceroplax 

 affinis Jeffr. FRIELE, Archiv. f. Math, og Naturvidenskab, ii, p. 313, 

 t. 5, f. 2 (Dentition). Machceroplax hidalgoi FISCHER, Jouru. de 

 Conchy 1. 1882, p. 51. 



A beautiful form, distinguished by the elevated turreted spire 

 bicarinate whorls, etc. The only specimens I have seen are from 

 the Gulf of Mexico. They are more elevated than Jeffrey's types. 



" A remarkable variety which I have named affinis (pi. 47, fig. 

 98), and at one time believed to be a distinct species, is finely and 

 closely reticulated ; the whorls are rounded and show no trace of 

 angularity ; and the umbilicus is not encircled by a keel." (Jeffreys.} 



According to Jeffreys, the M. hidalgoi Fischer is synonymous. 

 The original description is as follows : 



