Classification of the Bi'dc/i iojxida. — V// vc/yrt. 1 41^ 
8. Family Trimerkllid.?-:, Davidson and King 1874. 
? Lakmina, (Ehlert 1887. 
Davidsonella, Waagen 1885 
(notMunier-C'halmas 1880). 
Dinobolus, Hall 1871. 
Conradia, Hall MS. 1862. 
Obolellina, Billings 1871. 
TJngulites, Quenstedt 1871 
(not Bronn 1848). 
Monomorella, Billings 1871, 
Trimerella, Billings 1«62. 
Gotlandia, L)all 1870. 
Khvnobolus. Hall 1874. 
Family LiN<aTi.Ei>LiD.K,* n. fani. 
Lingulella, Salter 18(36. 
Lingulepis, Hall 1863. 
Leptobolus, Hall 1871. 
Paterula, Barrande 1879. 
C!yclus, Barrande 1879. 
?Mickwitzia, Schmidt 1888. 
2". Family Lincjulid.^^-, Gray 1840. 
Lingula, Bruguiere 1792. 
Pharetra, Bolton 1798. 
Lingularins, Dumeril 1800 
aiossina, Phillips 1848. 
Dignomia, Hall 1871. 
(xlottidia, ])all 1870. 
Barroisella, Hall 1892. 
Thomasina, Hall 1892. 
3'. Famil}' Linuulasmatid.k,! n. fam., Winchell and Schnchert, 
Lingnlops, Hall 1871. 
Lingulasma. IJlrich 1889. 
I>ingulelasnia. ^liller 1889. 
Order Neotremata,+ Beecher 1S91. 
Suborder Daikaulia,i< Waagen 1885. 
1. Family Trematid.*:, n. fam. 
Discinolepis, Waagen 188.'). I Schizobolus, Ulrieh 1886. 
*See foot-note to the Oboj.id^e. 
tThe species of this family are ijhitforiii-bearing liiigulii'. Interuallv their relations 
are with the Tiiimekei.lid.i-;, but the elongate shape and strongly phosphatic nature of 
their shells combined with their later appearance in geologic time give strong support 
to the view that they have originated from another phylum, the Linguliu^, rather than 
that which gave rise to the Tuimeijellid^k, the Obolu).*;. 
:J:"Pedicle fissure remaining open in primitive mature forms, becoming enclosed in 
secondary forms during nealogic stages, and in derived types enclosed in early nealogic 
or nepionic stages." 
§The suborder Daikaui.ia contains the inarticulate uncemented species in which the 
passage for the pedicle is through one valve during all nealogic and ephebolic stages of 
"rowth. In the Trematib.e is probably indicated one of the first steps from the 
OBOi,in>E towards the AcuothetiDxE. Succeeding growth to the ijrotegulum, in the 
former family, is not lioloperipheral, but ceases at its straight cardinal line, 
leaving, posterior to the protegulum, a more or less wide triangular notch in the ventral 
valve. In the Discinid^e, early growth is as in the Trematid.e, but before maturity is 
attained the two sides of the pedicle passage are gradually brought together, forming a 
long narrow depression in tile shell, at the anterior end of which the pedicle emergen. 
The reduction in size of the pedicle notch progressed rapidly in the Acuotketid.e to- 
wards a small circular perforation. In these families, the protegulum is invariably sit- 
uated at the anterior end of the pedicle passage, while in tin' dorsal valve it is marginal. 
In the SiPiioNOTUETiD.i-;, during younger stages of growth, tlie pedicle oi)ening was 
probably marginal, but long l)efore maturity is attained the opening is carried anteriorly 
through the iirotegulum and nepionic growth by resorption of ihe shell, wliile a deposi- 
tion takes place i)osteriorl\ undcTiii'atli the pedicle 
