AKA. SPI.| 



ANNELIDA. 



703 



SUBKINGDOM ARTICULATA. 



CLASS ANNELIDA. 



The Tubicola are invested in tubes to which they are not muscularly attached, 

 and the pakeozoic forms show no muscular scars. The tubes seem to have been 

 composed of calcite, and are generally found attached to some other object at the 

 apex or on one side. The jaws of the Conodonts are minute, glossy black, and 

 chitonous or horny, instead of being composed of calcite. Most of them, probably, 

 belong to the masticatory apparatus of Crustaceans. 



Arabellites aciculatus, and A. hindei, 



James, 1884, Jour. Cin. Soc. Nat. Hist., 



vol. 7, p. 148, Hud. Riv. Gr. 

 Cornulites sublams, Whiteaves, 1891, 



Cont. to Can. Pal., vol. 1, p. 210, Der 



vonian. 

 Polygnathus wilsoni, James, 1884, Jour. 



Cin. Soc. Nat. Hist,, vol. 7, p. 148, Hud. 



Riv. Gr. 

 Pkioniodus dychei, James, 1884, Jour. Cin. 



Soc. Nat. Hist., vol. 7, p. 147, Hud. 



Riv. Gr. 

 Sabellarites, Dawson, 1890, Quar. Jour. 



Geo. Soc, vol. 46, p. 605. [Ety. Sabel- 

 laria, a genus ; ites, from lithds, stone.] 

 Elongated tubes composed of grains of 

 sand and calcareous organic fragments 

 associated with carbonaceous, flocculent 

 matter, indicating a horny or mem- 

 branous sheath. Type S. trentonensis, 

 which is described at the same place 

 from the Trenton Gr., with S. phos- 

 phaticus from the Up. Taconic. 

 Spirorbis is generally more or less elevated 

 in the last whorl, and the aperture is 

 always turned up. 



•o+o- 



CLASS CRUSTACEA. 



The integument of the Crustacea (crmta, a crust,) is called chitonous; the seg- 

 ments or somites (soma, body,) are arranged longitudinally, and united transversely 

 by a membrane. The Cirripedia (cirrus, a curl ; pes, foot,) are attached to subma- 

 rine objects by the anterior end or metamorphosed head. The articulated cirri are 

 exserted and retracted from an opening at the posterior extremity. The Entomos- 

 traca (entomos, cut into; ostrakon, a shell,) have been denned as follows : Animals 

 aquatic, covered with a shell or carapace of a horny consistency, formed of one or 

 more pieces, in some genera resembling a cuirass or buckler, and in others a bivalve 

 shell, which completely or in great part envelops the body and limbs of the animal. 

 In other genera the animal is inverted with a multivalve carapace, like joiuted-plate 

 armor ; the branchiae are attached either to the feet or to the organs of mastication ; 

 the limbs are jointed and more or less setiferous. The animals, for the most part, 

 undergo a regular moulting or change of shell as they grow ; in some cases this 

 amounts to a species of transformation. The Ostracoda (ostrakon, a shell,) have the 

 valves united on the back by a membrane or ligament, and the valves are closed 

 by an adductor muscle, the place of attachment being indicated by a pit, group of 

 spots, or tubercle. Many genera have been recently described, some of them, appar- 



