UROCOPTIIXE. xiii 



The apex is comparatively large and bulbous, somewhat 

 globular in most Urocoptidcz. In some forms of Brachypo- 

 della it is specially modified. The protoconch is composed 

 of several whorls, and may be either smooth, or, by accelera- 

 tion, longitudinally ribbed, assuming sculptural characters 

 of a later stage of growth. This acceleration has been irreg- 

 ularly developed, occurring in many diverse phyla. This 

 gives aj)ical characters in Vrocoptidce less falue as indicating 

 the affinities of genera than in Bulimulida; but there is 

 probably much more in them than I have been able to utilize 

 in the systematic part of this work, from lack of sufficient 

 material. Collectors should especially look for immature 

 shells and amputated spires when collecting Urocoptidce, 

 and carefully preserve them with the adult shells they occur 

 with. The junction of the after-growth with the protoconch 

 is usually marked by some change in sculpture or by a slight 

 widening of the whorl at that place. 



The latter part of the last whorl, in most species of this 

 family, is straightened and built forward, carrying the aper- 

 ture to or beyond the level of the ventral face of the shell. 

 This necessitates the building forward of the columellar and 

 parietal margins of the peristorne, causing it to be continuous. 

 An entire peristome is of general occurrence, though in a 

 few genera (Anoma, Macroceramus, Microceramus, Pineria) 

 the peristome is discontinuous, as in Bulimulida. These 

 genera are not in the same phylum, and are highly and 

 diversely specialized in other respects, so that the interrup- 

 tion of the peristome in them is apparently a secondarily 

 acquired character. Throughout the series there is a ten- 

 dency to form an angle or keel where the outer wall passes 

 into the base, or on the base itself; but this feature is very 

 weakly developed in some genera, and absent in Holospira, 

 Epirobia, and a few other groups, probably by degeneration. 

 The presence of such a keel in most genera of the family 

 probably indicates it as one of the characters of the primi- 

 tive Urocoptida. In many forms the last whorl is partially 

 or wholly uncoiled, descending in a short or long neck. The 

 significance of this uncoiling will be alluded to below. It is 



