No. 398. ] WILLE Y ON THE ENTEROPNEUSTA. 129 
vascularity, they obviously constitute collectively the essential 
organs of respiration. In Amphioxus the functional impor- 
tance of the tongue bars is greatly diminished ; they are smaller 
in size and lower in vascularity than the primary bars, and their 
development is secondary." 
In certain of the Enteropneusta the ventral edges of the gill 
slits are swollen on the pharyngeal surface, and these thickened 
areas of the walls of the successive gill slits are continuous, form- 
ing a pair of lateral ciliated pharyngeal ridges. These “arch 
round in front to unite in the epibranchial band," and represent 
the endostyle of Amphioxus and the Tunicata. 
In one part of his memoir Dr. Willey describes certain phe- 
nomena of regeneration in Ptychodera flava, summarizing them 
as follows: 
(1) * When regeneration occurs in the region of the genital 
pleurz the collar is regenerated from the pleurze. 
(2) “ The collar nerve tube is formed by the fusion of true 
medullary folds which are differentiated from the pleural folds. 
(3) * The zones of the collar are differentiated from the annu- 
lations of the body wall. 
(4) “ In regenerating individuals the right and left proboscis 
pores are approximately equal. 
(5) “In regenerating individuals the lumen of the stomo- 
chord! is at first entire." 
I trust the absence of comment in this review upon some of 
the proposed theories will not be interpreted as indicating my 
acceptance of these theories. The paper is noteworthy for 
the boldness and confidence with which it sets forth startling 
propositions. 
THE Woman’s CoLLEGE OF BALTIMORE, 
January 9, 1900. 
1 Notochord of Bateson: 
