STUDIES ON THE PBOTOOHOEDATA. 325 



ferring to the pyloric gland of Ascidians and the caecum of 

 Araphioxus, it is stated that they both lie on the left side. 

 While they are of course essentially median outgrowths of the 

 alimentary canal, the caecum of Amphioxus usually lies for the 

 greater part of its extent to the right of the pharynx. Atten- 

 tion may, however, be drawn to Schneider's observation (^Beit. 

 zur vergl. Anat. und Entw. der Wirbelthiere,' Berlin, 1879, 

 p. 17, foot-note) that he often found it on the left side of the 

 pharynx. 



Finally, on p. 336 (eight lines from bottom of page) 

 " Trigeminus " should read '' Facialis." 



Addendum. 



Since the above contributions were sent into the press, 

 several new publications relating to kindred subjects have 

 appeared. 



1. A. Pizon, ina " Note additionnelle'^ appended to his long 

 treatise on the Blastogenesis of the Botryllidse (see ' Aunales 

 des Sciences Nat.,' 7me serie, t. xiv, p. 374, et seq.), expresses 

 doubt as to the accuracy of Hjort's and my results, and states 

 his own opinion that in the larvse of Botryllus, and in the buds 

 of many other forms, " I'organe vibratile est toujours un diver- 

 ticule de la vesicale endodermique primitive.'^ 



2. Hjort (" tJber den Entwicklungscyclus der zusammen- 

 gesetzten Ascidien," 'Mitth. Zool. Stat. Neapel,' x, pp. 

 584 — 617, Taf. 37 — 39) gives a detailed account of his re- 

 searches on the budding of Botryllus and the metamorphosis 

 of the nervous system of Distaplia. In the latter case his 

 observations agree in the most satisfactory manner substan- 

 tially with mine on Ciona and Clavelina. 



3. Da vi doff ("Uber den ' canalis neurentericus anterior' 

 bei den Ascidien," 'Anat. Anz.,' viii, pp. 301 — 303) objects to 

 the identification of the subneural gland of the Ascidians with 

 the hypophysis of the Vertebrates, and agrees with Kupffer 

 that the latter is homologous with the Tunicate mouth. 



4. Van Wijhe ("Ueber Amphioxus," 'Anat. Anz.,' viii, pp. 

 152 — 172) agrees with me in regardiug the club-shaped gland 



