H. H. NEWMAN. 



alies exhibited by the larvae of this species, such as twin gastrulae 

 and Bipennarice and numerous inhibited types. One would scarcely 

 choose such a species as a favorable object for the study of normal 

 development ; yet this very thing has been done by Heath, who in 

 1917 published an account of the early development of this species. 



/ 2 



FIG. i. A gastrula stage, which is obviously subnormal and is to be com- 

 pared with a normal gastrula such as is shown in FIG. 17. (After Heath.) 



FIG. 2. A larva in the stage of cutting off the hydroenteroccel pouches. 

 (After Heath.) a. p., apical plate; a. v,, anterior vesicle; I. p., left posterior 

 enterocoele pouch. 



Heath's account was, when it first appeared, very interesting to the 

 present writer because of the rather startling discovery of several 

 characters quite unknown for echinoderm larvae, but suggestive of 

 enteropneustan conditions. A brief account of Heath's findings 

 must be given in order that the reader may appreciate the present 

 contention. 



In the plankton of Monterey Bay a small number of gastrulse 

 were found which seemed to Heath to combine in a unique way 

 the characters of Echinodermata and of Enteropneusta. Various 

 starfishes were artificially fertilized and reared far enough to show 

 that the first captured plankton specimens were larvae of Patina 

 miniata. 



The artificially fertilized material was reared in finger-bowls and 

 it was found that " the segmentation and early blastula stages do 

 not exhibit any noteworthy features, but beyond this point certain 

 structures arise that have no known counterpart among starfishes. 

 The first of these unique organs is the apical plate. In the blastula 



