WITH NOTES ON THE WEST INDIAN SPECIES. 287 



eyes and the inferior dorsal lobe of the ciliated band (Text-figure 4). In my Tornaria 

 there is no such sharply defined lobe, but a groove passes continuously round from 

 the lateral lobe of the ciliated band across the dorsal middle line. This groove is 

 overhung by the anterior body of the Tornaria, and appears in fresh surface view as 

 little more than a line. 



In Morgan's Tornaria the dorsal edge of the lateral lobe is entire, there being 

 no inferior dorsal lobe proceeding from it. 



The egg of B. kowalevskii ("375 mm. in major diameter [Bateson]) is more than 

 six times as large as the egg of Pt. flava and more than four times that of Pt. 

 ruficollis. The egg of Peripetias capensis is not more than five times as large as 

 that of P. novae-britanniae, and the difference in the development of these two species 

 of Peripatus is precisely the difference between direct and indirect development 1 . 



Thus both in the Enteropneusta and in the Onychophora the forms whose anatomy 

 leads us to believe are the most primitive are those whose development is indirect, 

 and in both cases it is the indirect development which instructs us as to the proxi- 

 mate affinities of these comparatively isolated groups; while from the direct develop- 

 ment we are apparently able to gather information as to the primordial significance 

 of their organisation (e.g. blastopore of P. capensis and coelomic pouches of B. 

 kowalevskii). 



1 The fact that we can distinguish between direct and indirect development in an intrauterine environ- 

 ment is one of very great interest. 



W. III. 



40 



