LANG. HUBRECHT 301 



In 1882, before the publication of Sedgwick's papers, 

 A. Lang 1 had put forward the somewhat similar view that 

 the stomach-diverticula of the Turbellaria, which he had found 

 to be segmentally arranged in certain Triclads, were the 

 morphological equivalents of the enteroccelic pouches of 

 higher animals. This view, however, he soon gave up. 2 

 Sedgwick's views found a supporter in A. A. W. Hubrecht, 3 

 who utilised them in connection both with his speculations 

 on the relation of Nemertines to Vertebrates, and with his 

 exhaustive work on the early development of the Mammalia. 

 He postulated as the far-back ancestor of Vertebrates, " an 

 actinia-like, vermiform being, elongated in the direction of 

 the mouth-slit " (p. 410, 1906), and derived the central nervous 

 system from the circum-oral ring of this primitive form, the 

 notochord from its stomodaeum, and the ccelom from the 

 peripheral parts of the gastric cavity (p. 169, 1909). 



1 " Der Bau von Gunda segmentata,'' Mitth. Zool. Stat. Neap., iii., 

 pp. 187-250, 1882. 



2 "Die Polycladen," Fauna u. Flora des Golfes von Neapel, Monog. 

 v., Leipzig, 1884, and " Beitrage zu einer Trophocceltheorie," Jen. Zeits., 

 xxxviii., pp. 1-373, 1904 (which see for a modern account of theories of 

 metamerism). 



3 "'Die Abstammung der Anneliden u. Chordaten,"/<?- Zeits.) xxxix., 

 pp. 151-76, 1905. "The Gastrulation of the Vertebrates," Q.J.M.S., 

 xlix., pp. 403-19, 1906. "Early Ontogenetic Phenomena in Mammals," 

 Q./.M.S., liii., pp. 1-181, 1909. 



