246 



STUDIES IN EVOLUTION 



Leptoccdia. 



Leiorhynchus. 

 *Liothyrina. 

 * Macandrevia. 



Magas. 

 *Magellania. 

 *Martinia. 



Martinopsis. 



Megatliyris. 



Megalanteris. 

 *MegerUna. 



Merista. 

 *Meristella. 

 *Meristi7ia. 

 *Mulilfeldtia. 



Nucleospira. 



Pentagonia. 



Peregrinella. 



Platydia. 



Bensselceria. 



Reticularia. 



Betzia. 



* Bhynclionella. 

 Rhynclionellina 

 Rhynchoporina. 

 Rhynchotrema. 



* Rhynchotreta. 

 *Spirifer. 



Spiriferina. 

 Spirigerella. 



Stringocephalus. 



Suessia. 



Syringothyris. 



* Terehratella. 

 Terebratula. 



* Terebratulina. 

 Terebratuloidea. 

 Thecospira. 

 Trematospira. 

 Trigonosemus. 



* Tropidoleptus. 

 Uncinulus. 

 Uncites. 

 Zellania. 



* Zygospira. 



Part II. Classification op the Stages of Growth 

 AND Decline* 



(Plate XII) 



A BRIEF review of the known embryology of the Erachiop- 

 oda is desirable, in order to account for some of the differ- 

 ences presented by adult forms in the several divisions of the 

 class. This knowledge is far from complete, and is confined 

 to a few species, but much of interest bearing on the later 

 development of the organism may be obtained. 



The important memoirs f of Morse,^^' ^^ Kovalevski,^°Lacaze- 

 Duthiers,^^ and Shipley ^^ contain nearly all that is known 

 regarding the early embryology of brachiopods. The genera 

 included in the works of these authors comprise Cistella, 

 Terebratulina, Liothyrina, and Lacazella. Later larval stages 

 of the genus Grlottidia have been fully described by Brooks.* 

 Mliller,^'' also, has given a description and figures of a larval 

 form doubtfully referred to Discinisca. The results of these 

 observers must at present be taken without reservation, and 

 are thus made use of in the present paper. 



* Ajner. Jour. Sci. (3), XLIV, 133-155, pi. i, 1892. 



t The works referred to by numbers are cited in full in the list appended to 

 this article. 



