30 
Journal of the 
fications, which form the bases of Mr* Hmcks’ sections of the 
genus, are found in shoots of the same cluster, which in all other 
points of structure are identical, and they enable us to trace with 
ease the transition from one type to the other, though I can see 
no indication to show whether development has proceeded from 
the closed to the open corbulte, or vice versa. The closed forms 
consist of two series of pinnules, or leaflets, which bear a row of 
sarcothecae on their distal edges only, and which are completely 
united to each other throughout their whole length, forming a 
pod-like receptacle. When, however, each leaflet is separate and 
free, the sarcothecse are developed on both edges, though not 
always to the same extent, the proximal margin often being 
nearly free from them towards the base, while the pinnules 
occasionally appear to be slightly attached to each other at one or 
two points in the same part, though free throughout the rest of 
their length. It is noticeable that the pinnules in the open 
corbulse of A. plumosa and A . McCoyi , also of A. divaricate, Busk, 
are always devoid of sarcothecse on the proximal side, near the 
base.* 
Another point which I have not seen mentioned is the existence 
in certain species of minute, claw-shaped denticles, projecting into 
the cavity of the hydrotheca at or near the base, and forming two 
small groups or series. They appear to partly surround the 
opening which connects the cavity of the hydrotheca with that of 
the pinna, and may possibly serve as points of attachment for the 
hydranth. To distinguish them, it is sometimes necessary to heat 
* I have recently received from Mr. Goldstein a beautiful little Aglao- 
phenia from Fiji, which I mention principally on account of its peculiar 
corbula. The species is about an inch in height, light brown, branched, 
with straight, approximate, alternate pinmo; the stems without distinct 
joints, though towards the summit there are faint indications of them. Tho 
calycles are peculiar in form, lying along the pinnae, and deeply constricted 
in the middle of the upper side, the constriction representing the intrathecal 
ridge, which in some species occupies the same position, and which is simply 
a constriction with its walls coalescent, forming a partial septum. Tho anterior 
sarcotheca is rather long, rising principally from the calycle, and directed 
forwards and slightly upwards; the laterals are tubular, pointing forwards, 
and springing from under the calycle, so that their position is further towards 
the back of the pinna than is usually tho case; in both kinds tho terminal 
and lateral orifices are united by a narrow slit. Tho aperture is somewhat 
expanding, with three teeth on each side and an incurved one in front, and 
