164 VERMETID^. 



absorbed away by the animal, like the teeth of Pupa, and although 

 they are made subgeneric and sectional characters, they may be 

 present or missing in the same species, and are consequentl}^ of 

 inferior taxonomic importance. 



Prof. 0. A. L. Morch made a special study of the Vermctids^, 

 and to his papers in the Journal de Conchjdiologie, and particu- 

 larly in the Zool. Proceedings, London, 18G0-1862, we are in- 

 debted for the only scientific arrangement of them. Unfortunately 

 this author has endeavored to name and describe every slight 

 variation, and has thus amassed a large collection of forms, 

 varieties and species, subgenera and genera, the study of which 

 is even more perplexing than that of the specimens themselves. 

 His genera are here reduced to subgenera, his subgenera to sec- 

 tions. Illustrations ma}'^ be found in the folio volume of Chenu, 

 in Reeve's " Iconica " and Sowerby's " Thesaurus," but these 

 respective monographs are only partial in their scope, the two 

 latter being confined to Siliquaria, and leave much to be desired 

 on the score of completeness. 



Dr. Leon Yaillant {Researches on Lamarck''s species of the 

 Tubispirata in Nouv. Arch, du Museum^ vii, 1871), thus classifies 

 the Vermetidae : — 



A. Operculum wanting or rudimentary. 



1. Genus SERPULORBIS, Sassi. 



^ 1 (none. S. G. Thyacodes. 



Operculum ■{ 



C rudimentary. S. G. Bivonia. 



B. Operculum present and perfect. 



a. Shell smooth within. 



2. Genus SIPHONIUM, Gray. 



Concave, with (plain. S. G. Siphonium. 

 margins Ispinose. S. G. Stephopoma. 



Operculum \ Formed of ( non eroding. S. G. Yermiculus. 

 stacked up < eroding the body to which 

 . lamellae. Shell ( is attached. S. G. Spiroglyphus. 



