372 



Prof. Allman on the Morphology 



of these branches with their rows of nematophores to certain 

 graptolites with their rows of calicles is too obvious to be 

 overlooked. 



Fiff. 3. 



Hydrothecse of Aglaophenia pluma, with hydranths and fixed nemato- 

 phores. 



A. Hydrotheca with the hydranth extended and with the protoplasmic 



contents of the nematophores quiescent : a, hydranth ; c, serrated 

 margin of hydrotheca ; d, segment of the ramulus, carrying the hy- 

 drotheca ; e, mesial or azygous nematophore ; /, lateral nematophore ; 

 g, lateral aperture through which the cavity of the nematophore com- 

 municates with that of the hydrotheca. 



B. Hydrotheca with retracted hydranth and with the protoplasmic con- 



tents of the nematophores emitting pseudopodial prolongations : 

 a, hydranth ; c, margin of hydrotheca ; d, segment of the ramulus 

 carrying the hydrotheca ; e, mesial nematophore with its protoplasm 

 projected in an irregular pseudopodial mass, g, through its lateral 

 aperture into the cavity of the hydi'otheca ; f, lateral nematophore 

 with the conmiencement of a pseudopodium. 



C. Same parts, with pseudopodial processes more advanced. 



D. Same parts, showing different states of extension of the pseudopodia. 



