XXIV HISTORICAL NOTES. 



Cayman islands will, no doubt, illuminate these questions. 

 Ortmann ( '02, p. 360) postulates a later Tertiary connection 

 of the Greater Antilles with northern Central America, based 

 upon the occurrence of identical species of Potamocarcinus 

 (s.-g. Pseudothelphusa) in Mexico, Cuba and Haiti ; but since 

 this genus occurs in the Lesser Antilles also, its dispersal can 

 perhaps be explained in the same manner as that of Brachy- 

 podella. The anomalous distribution of the genus Archego- 

 coptis (vol. xv, p. 301) remains to be explained. 



The distribution of the Urocoptidce is favorable to Wal- 

 lace 's idea of an old mid- American continent. This Palaeozoic 

 and early Mesozoic land, including the Antillean and Central 

 American areas, divided in Mesozoic times into an Eastern 

 and a Western division, the Urocoptidce of the former giving 

 rise to the modern Urocoptincz, while the less modified group 

 Eucalodiince were evolved in the Western area. 



HISTORICAL NOTES ON THE CLASSIFICATION OF UROCOPTID^E. 



I. 



Before the year 1840, when Pfeiffer established the genus 

 Cylindrella, the few species of Urocoptidce known were scat- 

 tered in several genera. The earliest records of species of 

 this family are certain rude figures in the works of Petiver 

 and Lister (1665), evidently representing Jamaican and Hai- 

 tian forms, though their specific identity is somewhat un- 

 certain. No species were known to Linne. In 1786 Chem- 

 nitz figured and described a Haitian form as Helix decollata 

 et fasciata, and later a Jamaican species, Turbo cylindrus, 

 both being recognized by recent naturalists. About the end 

 of the second decade of the nineteenth century, Ferussac 

 issued his Tableau Systematique, in which about seventeen 

 species referable to the Urocoptidcz are enumerated, though 

 part of them were at this time undefined names. He places 

 them in the sections Pupoides, Tracheloides and Anomales, 

 of Cochlodina, a subgenus of Helix, also comprising Clausilia t 

 Balea, and an Odontostomus. Ferussac clearly appreciated 

 the relationship to one another of the various species of the 



