181 



-D 



The important surface features of the shell are: the lines of growth, 

 the radiating plications or striatimis, Wwfolil or medial elevation, and the 

 sinttH or medial depression, the fold commonly occurring in the brachial, 

 and the sinus in the pedicle, valve. 



The following diagram represents the principal features of the shell, 

 and gives its orientation. 



Note. — For an account 

 of the anatomy of the ani- 

 mal, any text-book of 

 zoology may be consulted. 

 Zittel's text-book of Pahe- 

 ontology (Eastman's trans- 

 lation) is standard. For 

 the best account of the 

 animal and the shell, as 

 well as detailed descrip- 

 tions of the genera, the 



student is referred to the 



.,],„.• ol .i. .,„ i i.„„i. „ f Fig. 78. Diagram of Spirifer. (A, B) Longitudi- 



aumirauie uauu-uooK. oi na i ax j s mar king the height :( C\ Z> ) Transverse axis 



the Brachiopoda, by Hall marking the width: ( B) anterior (front )end; (A J pos- 



. terior or beak end ; ( ar. \ cardinal area ; ( b ) beak 



and Clarke, entitled "An i or umbo i ; (Br.) brachial valve ; ( car. si. ) cardinal 



intrnrliiftimi tr, Hie Qtn.lv slopes ;( ce > cardinal extremities ;( del.) delthy riura ; 



introduction to tne siuuj ( /c/. , mesial fold of brachial valve ; ( hg. ) hinge-line : 



of the Brachiopoda," and ( Ped.) pedicle valve ; (pi.) plications;, [si.) mesial 



sinus of pedicle valve. (^Original.) 

 published in the reports of 



the State Geologist of New York, for 1891 and 1893. Vol. VIII. , Pts. I. 



and II., of the Palaeontology of New York, should also be w-ithin the reach 



of the student. 



The specific descriptions will nearly all be found in Vol. IV. of the 



Palaeontology of New York, and for a more detailed study that volume 



should be consulted. For classification, synouomy, and distribution 



consult "A Synopsis of American Fossil Brachiopoda," by Charles 



Schuchert. Bull. 87, U. S. G. S. In the preparation of the following 



brief descriptions the above-named sources have largely been drawn 



upon. 



BRACHIOPODA INARTICULATA. 

 Genus LINGULA. Bruguiere. 



[Ety. : Lincjula, a little tongue.] 



(1789: Hist. Natur. des Vers Testaces. 1892: 

 Vol. VIII., Pt. I., p. 2.) 



Pal. N. Y., 



Shell with the valves nearly equal, and varying in outline 

 from elongate-ovate to sub-triangular, always longer than 

 wide. Valves arched. Animal attached by a long, muscular 

 pedicle, which protrudes from between the beaks of the two 

 A r alves. 



