516 



ANNELIDA. 



[VEN. — YOIy. 



inconstans, Billings, 1858, Rep. of Progr. 



Geo. Sur. Can., p. 186, Black Riv. and 



Trenton Grs. • 

 montrealensis, Billings, 1859 Can. Nat. 



and Geol., vol. 4, p. 444, Chazy Gr. 

 tomkinsi, Billings, 1860, Can. Jour., vol. 



6, p. 357, Up. Held. Gr. 

 Venus moJwgan, Castelnau, 1843, Syst. Sil., 



p. 44. Not recognized. 

 Vektumnia. Hall, 1884, Pal. N. Y., vol. 5, pt. 



1, p. xii. Proposed as a subgenus of 

 Pterinea, distinguished by having the 

 right valve convex, and the left flat or 

 concave ; hinge area narrow. The spe- 

 cies referred to it are Pterinea avis, P. 

 reproba, and P. reversa. 



Yoi.oia, Muller, 1842. Kroyer's Nat. Tid., 

 vol. 4, p. 91. [Ety. proper name.] 

 Shell ovate or subelliptieal, subeqni- 

 lateral, compressed ; posterior side 

 narrower than the ottier; surface 

 smooth, striate, or obliquely sculptured, 

 and covered with a polished epidermis; 

 margins smooth within; inner laminae 

 pearly ; hinge plates small, numerous 

 on each side of the beaks ; cartilage pit 

 under the beaks; pallial line sinuous. 

 Type Y. nivalis, 

 carbonaria, Meek, 1871, Rep. Reg. Uni- 

 versity W. Va., p. 6, and Ohio Pal., vol. 



2, p. 336, Coal Meas. 



Fig. 935.— Yoldia 

 myalls. 



gibbosa, McChesney, 1859. The name was 

 preoccupied. See T. rushensis. 



knoxensis, McChes- 

 ney, 1865, (Leda 

 knoxensis,) Expl. 

 Pal. Foss., pi. 2, 

 Coal Meas. 



levistriata, Meek & 

 Worthen, 1860, 

 (Leda levistriata,) 

 Proc. Acad. Nat. 

 Sci. Phil., p. 457, and Geo. Sur. 111., vol. 

 2, p. 282, St. Louis Gr. 



oweni, McChesney, 1860, (Leda oweni,) 

 Desc. New. Pal. Foss., p. 52, Coal 

 Meas. 



polita, McChesney, 1859. The name was 

 preoccupied, see Y. knoxensis. 



rushensis, McChesney, 1865, (Leda rush- 

 ensis,) Expl. Pal. Foss., pi. 2, Coal 

 Meas. 



stevensoni, Meek, 1871, Rep. Reg. Uni- 

 versity W. Va., p. 6, and Ohio Pal., vol. 

 2, p. 335, Coal Meas. 



subscitula, Meek & Hayden, 1858, (Leda 

 subscitula, Trans. Alb. Inst., vol. 4, p. 

 79, and Pal. E. Neb., p. 205, Per- 

 mian Gr. 



valvulus, Hall & Whitfield, 1872, 24th 

 Rep. N. Y. Mus. Nat. Hist., p. 190, Up. 

 Held. Gr. 



•o+o« 



SUBKINGDOM ARTICULATA. 



The Articulata are the most numerous of all living animals, and abound alike 

 on land and sea. They are divided into Classes, Subclasses, Orders, and Suborders. 

 Many of them possess intelligence, arising from ganglionic centers, and in the sum- 

 mer season provide their food for winter. Several living orders are unknown in 

 Palaeozoic rocks; this may have resulted, however, from want of preservation. 

 The fossils belong to the Classes Annelida, Crustacea, Arachnida, Myriapoda, 

 Insecta. 



CLASS ANNELIDA. 



The Annelida have the bodies divided into segments, which are generally fur- 

 nished with jointed appendages. The living forms are distributed in four Orders, 

 but no such division is practicable with the Palaeozoic fossils, where generally only 

 the internal jaws, called Conodonts or worm-burrows, are found preserved. The 

 Conodonts may be the internal jaws of Crustacea, as seems to the author most 

 probable ; but there is no ground for referring them to fish, as has been done by 

 some authors. The class may be divided as follows : 



Conodonts. — Arabellites, Distacodus, Drepanodus, Eunicites, Glycerites, Lum- 

 briconereites, Nereidavus, Oenonites, Polygnathus, Prioniodus, Stauro- 

 cephalites. 



