246 



STUDIES IN EVOLUTION 



Leptocoelia. 



Leiorlujiiclms. 

 *Liotliyrina. 

 *Macandrevia. 



Magas. 



* Marjellania. 

 *Martinia. 



Martinopsis. 



3fegathyris. 



Megalanteris. 

 *Megerlina. 



Merista. 

 *3feristella. 



* Meristina. 

 *Mulilfeldtia. 



Nudeosjn'ra. 



Pentagonia. 



Peregrinella. 



Platydia. 



Rensselceria. 



Reticularia. 



Retzia. 



* Rhynchonella . 

 RhyncJionellina 

 Rhynclioporina. 

 Rhynchotrema. 



* Rhynchotreta. 

 *Spirifer. 



Spirlferina. 

 Spirigerella. 



Stringocephcdus. 



Suessla. 



SyringotJiyris. 



* Terebratella. 

 Terehratula. 



* Terehratidina. 

 Terebratuloidea. 

 Thecospira. 

 Trematospira. 

 Trigonosemus. 



* Tropidoleptus. 

 Uiicinulus. 

 Uncites. 

 Zellania. 



* Zygosp)ira. 



Part II. Classification of the Stages of Growth 

 AND Decline* 



(Plate XII) 



A BRIEF review of the known embryology of the Brachiop- 

 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 CisteUa, 

 Tei-ebratulina, Liothyrina, and Lacazella. Later larval stages 

 of the genus G-lottidia have been fully described by Brooks.* 

 Miiller,^'^ 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. 



* Amer. 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. 



