352 GENERAL SUMMARY TO 



I have included in the Zingulida the genera Lingula, Lingulella, Glottidia, Glossina, 

 Dignomia ; Lingulops is with some uncertainty placed among the Lingutida (see the paper 

 by King and myself " On the Trimerellida " (' Quart. Journ. Geol. Soc.,' p. 167, 1874). 

 The characters made known evidently relate it both to the Trimerellida and Lingulidce ; 

 but while thus allied, we felt undecided as to the family it should be placed in. Hall 

 has proposed a genus Dignomia for a Lingula having a longitudinal septum in both 

 valves, which occurs in the Lower Silurian and Devonian (' Twenty -third Report on the 

 State Cabinet for 1871.') Phillips has proposed the genus Glossina for such shells as 

 Lingula crumena, L. attenuata, and some others, but the differential characters have not 

 been sufficiently determined to warrant its admission, and he gives no diagnosis (see ' Mem. 

 Geol. Survey of Great Britain,' vol. ii, part i, p. 370, 1848). 



In the second family {Obolida) Dall places Spondilobolus, M' Coy; Monobolina, Salter; 

 Kutorgina, Billings ; Obolella, Billings; Aulonotreta, Kutorga (pars) ; Helmersenia, Pander; 

 and Keyserlingia, Pander. It is an assemblage of widely different things, and as to the 

 correct position of some of them I still feel uncertain. 



In 1830 Pander proposed a genus XJngula ('Beitr. Geogn. Russ. Reiches,' pp. 55-7, 

 type U. convexa, Pander = Obolus apollinis, Eichwald, 18.29 (' Zool. Specialis,' i, p. 

 274, tab. iv, fig. 5). As Eichwald's generic name of Obolus was published one year 

 previous to that of Pander it will require to be retained in preference to its synonym 

 Ungula. In 1848 Bronn proposed a genus Lingulites, but it cannot be adopted. 



Dall in the 'American Journal of Conchology,' vol. vii, part 2, p 74, 1881, and in 

 the ' Proceedings of the Phil. Acad. Nat. Sciences,' p. 200, July, 1873, divided the genus 

 Discina into Discina proper, Lamarck, ' Hist. Nat. des Animaux sans Vertebres, 5 vol. vi, 

 p. 256, 1819, type Discina ostrceoides = D. striata ; and he proposed another genus or 

 sub-genus, Discinisca, for such shells as D. lamellosa, Brod. It is, however, difficult in 

 many cases among the fossil forms to feel certain to which of these groups such and such 

 a shell should be referred, and to define correctly their respective stratigraphical ranges 

 from the Cambrian up to the recent time. 



I am uncertain with respect to the generic value of Hall's genus Schizomania (' Pal. 

 Ohio,' vol. ii, p. 71, 1875). Dall in his " Index to the Class Brachiopoda," p. 61, places 

 it among the Discinida and says, " The lower or flat valve is deeply notched on the 

 posterior side of the centre, the notch extending from a point more or less distant from the 

 centre of the valve to the posterior margin, where the sides of the slit are widely and 

 distinctly separated, type S.filosa." I am uncertain whether it is a Brachiopod at all. 

 What is figured as the ventral valve seems referable rather to a species of Discinocaris. 



Although five genera have been classed in the Family Craniidce, I am not yet quite 

 satisfied with respect to the generic importance of Pseudocrania, M'Coy ; Craniopora, 

 Schauroth; and Ancistrocrania, Dall. They are admitted by Dall in his table of distri- 

 bution, and may prove to be good genera. 



Some uncertainty may prevail as to Volborthia, Moller, and Kutorgina, Moller, being 



