338 E. W. MACBRIDE. 



ing is represented in fig. 6. In this stage of E. esculentus 

 there are three pedicellarise, one at the posterior pole and two 

 on the right side posterior to the ciliated band ; the oral disc 

 of the adult has encroached very much upon the stomach, and 

 both the anterior and the posterior ciliated epaulettes are well 

 developed : the posterior by coalescence have formed a con- 

 tinuous ring. The cilia covering these epaulettes are much 

 more powerful than those on the ciliated band, and the epau- 

 lettes form in later larval life the main organs of locomotion ; 

 their appearance in the living animal when expanded recalls 

 the trochal disc of Rotifera. 



The " echinoplutei ^' larvae (to use Mortensen's term) are 

 distinguished from the more primitive bipinnarise by an im- 

 mense reduction of the prseoral lobe (Mortensen's frontal 

 area). Under these circumstances it is interesting to find a 

 remnant of this primitive structure surviving in the larvae of 

 E. miliaris, which develop from small eggs, and it is further 

 interesting to note that this primitive feature is most strongly 

 marked in the early stages of development. 



Montreal; Oct. 15th, 1898. 



Works beferred to in this Paper. 



1. Bury, H. — " The Metamorphosis of Echinoderms," 'Quart. Journ. Micr. 



Sci.,' 1895. 



2. MoRTENSEN, Th. — ' Die Echiiiodermeu-Larven der Plankton Expedition,' 



Kiel and Leipzig, 1898. 



3. MiJLLER, JoH. — " Die Larven der Echinodermen," several papers, ' Ab- 



handlungen der Kgl. Akademie der Wiss. zu Berlin,' 1848 — 1855. 



4. Theel, H. — " The Development, of Echinocyamus pusillus," 'Trans. 



Roy. Soc. Upsala,' 1892. 



