goldschmidt's monograph of amphioxides. 591 



are the more primitive on that account.^ lu the same way it 

 seems to me to be improbable tliat Amphioxides is primi- 

 tive in respect of the absence of an atrial chamber, of anti- 

 meres to the gill-slits, and of the hepatic caecum. 



Another unexpected conclusion to which Dr. Goldschmidt 

 has been led by his researches is the virtual denial of the 

 homology of the hepatic ceecum of the other Acrauiates with 

 the liver of Craniota, but he does not refer to recent work on 

 this organ." 



Turning now to the cavities in the rostrum of Amphi- 

 oxides we find a remarkably clear account of their relations 

 to each other and of their connections with the cavities 

 (myococl) of the first pair of myotomes. The special character 

 of these myotomes, as compared with those which follow, 

 has been pointed out by Hatschek (1881), and more recently 

 by MacBride (1897), who compared them with the collar 

 cavities of Enteropneusta. 



The diagram (fig. 4) and the transverse section (fig. 5) 

 illustrate the arrangement, which is sufficiently elucidated in 

 the explanation of the figures. Perhaps the most important 

 fact to note is that the ventral rostral cavity is that which 

 represents the right head-cavity of the embryo; it is aptly 

 desci-ibed as the ontogenetic partner of the preeoral pit, for 

 which it provides a splanchnocoel and a visceral musculature. 



From the mode of branching of the cephalic nerves, their 

 relation to the ventral rostral cavity, and the alleged pro- 

 somital gill-clefts of A. valdivia3, Dr. Goldschmidt deduces 

 a scheme of the segmentation of the head, for the particulars 

 of which the reader should consult the original monograph. 

 I regret that I cannot follow it myself, chiefly because I 

 cannot believe that there is such a fundamental difference 

 between closely-allied species as would follow if it were 

 actually true that A. valdivias is the possessor of pro- 



1 Of. H. Lohmanu, 'Die Appeudicularieu der Plankton-Expedition,' Kiel 

 and Leipzig, 1S96. 



- Guido Sclineider, "Eiuiges iiber Resorption und Excretion bei Amplii- 

 oxus lanceolatus, Yarrell," ' Anat. Anz.,' xvi, 1S99, pp. 601—605. 



