A COLLECTION OF HYDROIDS. 



311 



pair {ah.li.). Tliere is also occasionally a little peg of cliitiu 

 on the outer wall a little above the base {I.})-)- 



Total length, measured parallel to the abcauline edge, 

 0'263 mm. ; greatest breadth O'lOo mm. Operculum probably 

 two flaps. 



Hy dranth. — Tentacles 13-14. The layer o£ ectoderm lining 

 the hydrotheca is thickened along the outer margin (fig. D, 

 72-.), and it contains a. row of vertically placed nematocysts, 



Text-fig. 10. 



A(nat.siz,e) 



Sertularia bideus Bale. 



measuring 6"6 fx in length and 1'4 /n in breadth. Nematocysts 

 Avere not distinguished on the tentacles. 



There is also a thickening of the hydrothecal ectoderm on 

 the adcauline surface (D, tli.). 



GrONOSOME. — Gonangia long, sub-tubular, Avith Iavo sharp 

 angles at the sides of the aperture. Aperture operculate, 

 margin elevated and slightly everted. The gonangia originate 

 from the stem just above the origins of the pinna^, and they 

 are reorularlv directed risfht and left. 



