286 LEPTINARIA. 



The resemblance should be noted of the lengthened ovip- 

 arous Leptinarias to certain forms still included in Opeas, 

 section Tomopeas (p. 123). These Eastern forms may really 

 belong to Leptinaria, yet I hesitate to transfer them until 

 more is known of the soft anatomy of Leptinaria and Opeas. 



Leptinaria is an extensive and widely-spread genus in 

 tropical America. It comprises shells of widely diverse 

 shapes, yet excepting the aberrant groups Ischnocion and 

 Pelatrinia, the extremes are closely connected by intermediate 

 forms. Some of the species closely resemble Subulina; others 

 approach Opeas; so that the reference of certain species to 

 one or another of these groups becomes a matter of opinion 

 rather than of demonstration in the present stage of our 

 knowledge. The resemblance to Ochroderma is more super- 

 ficial, that genus having diverse characters in the early whorls. 

 Tornatellina differs fundamentally from Leptinaria in den- 

 tition, as Binney and Fischer have shown. 



The species are numerous, many of them critical and diffi- 

 cult to diagnose ; and the more widely distributed forms have 

 been described and named again and again. Many nominal 

 species have been herein reduced to synonyms; but I have in 

 each case given the evidence for my views. The excellent 

 work of von Martens has been followed in dealing with the 

 Mexican and Central American forms. 



The series before me demonstrates, against my preconceived 

 opinion, that some species vary from completely imperforate 

 to openly perforate. This is notably the case with the An- 

 tillean ovate forms. The size and length of the parietal 

 lamella, when present, are also variable among individuals of 

 the same colony. In some species (as L. stolli) a parietal 

 lamella is present in the young, but not in adult shells ; other 

 forms (L. lamellata) have the parietal lamella at all stages 

 of growth from the embryo on. This subject calls for further 

 investigation with good series of shells from young to the 

 adult stage. It is only by such studies that the relations and 

 significance of the species can be ascertained. 



