. 
ON THE REPRODUCTIVE SYSTEM IN THE HYDROIDA. 379 
In the earliest stages of these leaflets their edges are entire (A «), but they 
soon become deeply serrated by the formation of hollow tooth-like processes 
(Fc) upon the edge which is turned towards the distal extremity of the ra- 
Fig. 13.—Development of the Corbula in Plumularia (Aglaophenia) pluma. 
l@ a@ 
A, very young corbula; B, corbula more advanced ; C, corbula in a still more advanced 
‘stage; D, the mature corbula; B, transverse section of mature corbula, showing two 
_gonangia, each containing a single gonophore. 4, leaflets of corbula ; , gonangia; c, ra- 
mulus supporting the leaflets; d, a hydrotheca. 
__ F, separate leaflet from mature corbula. a, continuation of the somatic cavity into the 
leaflet, where it divides into two branches, 2 4; ¢, nematophores forming tooth-like 
"processes on the distal edge of the leaflet ; d, imperfectly developed tooth-like processes on 
the proximal edge; e, septum dividing the cavity of the leaflet. 
G, gonangium from mature corbula. @, continuation of somatic cavity into gonangium ; 
2, blastostyle, partially suppressed by the enlarging gonophore; ¢c,gonophore; d, spadix ; 
J, ovum ; g, wall of gonangium. 
