STINGING-CELLS IN CRASPEDOTE MEDUSJ3. 781 



of the tentacles in the ectoderm of the conspicuous ocellar 

 bulbs at the terminations of the radial canals. 



(3) There is reason to believe that the bulbous swellings 

 at the bases of the tentacles have this function throughout the 

 craspedote Medusa. In the sub-divisions Trac homed usee 

 and Narcomedusse, they are probably replaced by the 

 thickened ring of thread-cells on the margin of the bell. 



(4) The development of the gonophores of Mcerisia takes 

 place in the manner described by Goette for other hydroids. 

 There is no double-walled cup of endoderm at any stage, the 

 radial canals and the endoderm lamella being derived from 

 four separate pouches of endoderm, which grow out simul- 

 taneously from the coelenteron of the simple bud. 



(5) The stinging-cells of this medusa are developed from 



cells, which, like the sex-cells, arise directly or indirectly from 



the ectoderm of the parent hydranth. 



Birmingham, 



June 19tli, 1910. 



Bibliography. 



This bibliography includes only those works actually mentioned in 

 the test of my paper; for a more complete list of literature I must 

 refer the reader to the memoirs of Hadzi (4) and Goette (11). 



1. Murbach, L. — "'Beitrage zur Kenntnis der Auatomie und Entwicke- 



lung der Nesselorgane der Hydroiden," ' Arch. f. Naturg.,' Jahrg. 

 60, Bd. i. 



2. Schneider, K. 0. — " Mittheilungen liber Siphouophoren : Y, Nessel- 



zeUen," " Arb. Zool. Inst. Wieu,' Tom. xii, 1900. 



3. ■' Histologic von Hydra fusca," 'Arch. f. Micr. Anat.,' 



Bd. XXXV, 1890. 



4. Hadzi, J. — "Ueber die Nesselzellwanderung bei den Hydroid- 



polypen," ' Arb. Zool. Inst. Wien,' Tom. xvii, 1907. 



5. Boulenger, C. L. — "On Mcerisia lyonsi, a new Hydromedusan 



from Lake Qurun," ' Quart. Journ. Micr. Sci.,' vol. 52, 1908. 



6. Hertwig, O., and R. — 'Das Nervensystem und die Sinnesorgane 



der Medusen,' Leipzig, 1878. 



7. Giinther, R. T. — "A further Conti'ibution to the Anatomy of 



Limnocnida tanganyicse," 'Quart. Join*n. Micr. Sci.,' vol. 

 36, 1«94. 



