I 29 



(;). The structure of the collar-pores or collar-canals is describcd, aiul il is shewn that they 

 are closely related with i)arts of the muscular system; suggesting that their modus 

 op e rand i is partly due to muscular actioii. 



(8). The stalk differs widely in proportions in the several species, and is specially long and 

 slender in C. gracilis and in C. sibogae. 



(9). The structure of the pharynx is described, and the probable mode of feeding is 

 considered. 

 (10). The most important constituents of the vascular system are (a) a large dorsal vessel 

 applied to the dorsal surface of the pharynx, and sending off vessels to the gonads; 

 '^b) the anterior and posterior vessels of the stalk. The anterior stalk-vessel is continuous 

 with the corresponding vessel of the trunk. The posterior stalk-vessel ends on the wall 

 of the second stomach, and is probably in communication with the dorsal vessel through 

 a perigastric sinus. 

 (11). Some account is given of the early development, which appears to shew some resemblances 

 to that of the large-yolked species of Balanoglossus. The five coelomic spaces of the adult 

 can be recognised in the embryo. The latest embryos are not old enough to give any 

 indication with regard to the mode in which most of the adult characters are acquired. 

 The two species investigated {C. gracilis and C. levinseni) differ to a striking extent in 

 some of their embr^'onic characters. 



(12). A partial account is given of the budding, in C. gracilis and in C. dodecalophtis. The 

 position of the parts of the alimentar)' canal of the bud shews some approach to the 

 condition found in Enteropneusta, the pharynx and stomach lying in the morphologically 

 antero-posterior line. 



(13). Cep halodiscus shews unmistakeable affinities to Rhabdoplctira and to the Enteropneusta. 

 It is probably related to Phoronis\ and, through Balanoglossus, to the Echinodermata 

 and the Chordata; but it is not nearly related to the Polyzoa. 



[Postscript. — An interesting note by Schepotieff (05) on Rhaódopleura has appeared just 

 as this sheet was about to be printed off. The paper contains important results 

 with recrard to the body-cavities, proboscis-pores, pleurochordal grooves, pericardium, 

 vascular system, muscles, testis and budding, and it appears to me to complete 

 the proof of the fundamental resemblance in structure between Rhaódopleura and 

 Cephalodiscus. The extra-oral parts of Schepotieff's "Kiemenrinnen" are what I 

 describe as the "food-channels" in this Report. The alimentary canal of the bud 

 is developed partly from an endodermic "Anlage", and not as I suppose it to be 

 developed in Cephalodiscus]. 



SIBOGA-EXPEDITIF. XXVI /'/.t. I? 



