120 



SYNOl'SIS OF AMERICAN FOSSIL BRACIIlorODA. [bull. 87. 



l)etlic']e grooves. Muscular scars distinct, consistiug of two pairs of 

 adductors and three of sliders, or adjustors. 



Obolella Billings, 1861. Acritis Volborth, 1809. 



Dicellomus Hall, 1871. Scbmidtia Volbortbjl809(not Bals- 



Elkania Ford, 188G. ^I'iv., 1863). 



Billinjrsia Ford, 1886. Tliysanotos Mickwitz, 1896. 



Feobolus Waagen, 1885. Leptembolon Mickwitz, 1896. 



Botsfordia Mattbew, 1893. 

 ?Spondylobolus McCoy, 1852. 

 Obolus Eicbwald, 1829. 



Ungiila Pautler, 1830. 

 Ungulites Bronn, 1848. 

 Anlontreta Kntorga, 1848. 

 Eiiobohis Miekwitz, 1896. 



3. Family TRIMERELLID.E Davidson and King, 1874. 



Large, tbick-sbelled, inequivalved Obolacea, with the ventral cardi 

 nal area usually very prominent, triangular, and transversely striated. 

 Adjustors and anterior adductor muscles elevated upon solid or deeply 

 excavated platforms, or spondylia. 



?LakminaCEblert, 1887. 



Daviclsonella Waagen, 1885 (not Mu- 

 nier-Chalmas, 1880). 



Lingulobolus Mattbew, 1896. 

 SpbiProbolus Mattbew, 1896. 

 Dinobolus Hall, 1871. 



ConradiaHall, MS., 1862. 

 Obolellina Billings, 1871. 

 Ungulites Quenstedt, 1871(^n()t Bronn, 



1848). 



Monomorella Billings, 1871. 

 Trimerella Billings, 1862. 



Gotlandia Dall, 1870. 



Rbinobolus Hall, 1874. 



Superfamily LINGULACEA Waagen, 1885 ( restricted ).i 



Elongate, tbin-shelled, burrowing, derived Atremata, with a more or 

 less long, worm-like, tubular, flexible pedicle. 



1. Family LINGTJLELLTD.E Scbucbert, 1893. 



Spatulate, inequivalved Lingulacea, structurally intermediate between 

 the Obolidse and Lingulid;^. 



Lingulella Salter, 1866. 

 Lingulepis Hall, 1863. 

 Leptobolus Hall, 1871. 



!Paterula Barrande, 1879. 



Cyclus Barrande, 1879. 

 ?Mickwitzia Schmidt, 1888. 



' Waagen'a term Mesokaulia, or Lingulacea, is based upon the families Obolidse, Trimerellida', and 

 Lingiil'dic. Since this term has value, and to avoid jiroposing another, Lingulacea is here restricted 

 to the latter family and two others recently proposed. AVaagen in using this term gave a dual series ; 

 the second one is here adopted to conform in euphony with other superfamily terms. 



