50 NATURAL SCIENCE. Jan.. 



Dall suggested in 1891.3 The following subdivisions of the great 

 family Terebratulidse, which we should place in the following order, 

 were proposed by CEhlert in 1887 :— Terebratulinae, Centronellinse, 

 Magasinae, Muhlfeldtinae, Terebratellinae and Magellanae. The present 

 investigations confirm this grouping. The genus TcrehvaUda of the 

 first-named and CentvoncUa of the second are the more ancient terebra- 

 tuloid types, and were represented in the Silurian seas. 



Messrs. CEhlert and Fischer received the materials for their re- 

 search on the Brachiopoda of the Magellanian province too late to 

 permit of the publication of their conclusions in the series of memoirs 

 relating to the French scientific mission to Cape Horn, during which 

 the " Romanche " dredged often in many localities. Few species 

 _were obtained, but the number of individual specimens of different 

 ages was large, and afforded them much desired opportunities for 

 studying the metamorphoses of the loop and gradational development 

 of Terebratella dorsata and Magellania venosa. The knowledge thus 

 gained, it is distinctly stated, should tend to the suppression of many 

 so-termed species and some assumed generic forms, for " the more the 

 Brachiopoda are studied the more the number of legitimate species will 

 decrease." It is demonstrated that the same individual in the course 

 of its post-embryonic development assumes successive stages which 

 are identical with both specific and generic forms of various authors. 

 Thus it is fully proven that the genera Waltonia (Davidson) and Magasella 

 (Dall) are really immature Teyebratellce in which the brachial apparatus has 

 not completed its development. Gould's Tevehratella pnlvinata is shown 

 to be merely a stage of Magellania venosa, which is not permanently 

 arrested in the terebratelliform grade like its congener Terebratella 

 dorsata, but assumes ultimately the characteristics oi Magellania venosa. 

 This is a fine but variable species with a large number of synonyms 

 whicii have been well worked out by Davidson. Messrs. CEhlert and 

 Fischer state that it attains maturity early, and its complete evolution 

 was observed by them in specimens 27 mm. long in which all traces 

 of the jugal band had disappeared. The largest known specimen 

 measures 3 inches 2 lines in length and 2 inches 8 lines in breadth. 

 Magasella gouldi becomes Tevehratella goitldi, but it is not yet known 

 whether it stops there or eventually assumes the generic characters of 

 some species of Magellania. It is certain, however, that Magasella 

 evansi is but a phase of Terebratella criienta. Magasella patagonica, M. 

 dexuosa, and M. suffusa name different ages of Terebratella dorsata, M . 

 Icrvis another stage of Magellania venosa, while M . adamsi first becomes 

 terebratelliform and eventually passes into Magellania grayii (4). 



In the course of these investigations the important physiological 

 facts of accelerated growth were recognised. Owing to favourable 

 conditions of the environment, some adolescent individuals were 



^ The name Terebratnlina was accidentally printed for TerebratelUua on line 19, p. 

 603, of my paper " Recent Researches on the Brachiopoda," in Natural Science, 

 October, 1S92 The error escaped notice. 



