AGLAOPHENIA APOCARPA. 41 



which the leaflets of the corbula give oflF at their base form a series of 

 pinna? upon each side of the rachis, very obvious when the corbula is viewed 

 either from above or below. These pinnte-like processes carry nemato- 

 phores along their upper side, and when viewed from below are seen to 

 send off a somewhat triangular, flat, wing-like expansion from the lower. 

 The beak-like extension of the rachis carries also on its upper surface 

 nematophores which are disposed in two pairs. The peduncle of the cor- 

 bula carries a single hydrotheca. 



Aglaophenia lophocarpa. 

 PI XXI r. Figs. 1-4. 



Trophosome. — Hydrocaulus attaining a height of between two and three 

 inches, simple, not fascicled ; pinna? alternate, springing from a point near 

 the distal end of each internode. Hydrotheca? deep, somewhat tumid below, 

 margin slightly everted, with nine equal very distinct teeth ; intrathecal 

 ridge transverse. Siipracalycine nematophores slightly overtopping the 

 hydrothecie ; mesial neraatophore adnate to within a very short distance 

 of its summit, and attaining nearly half the height of the hydrothecas ; 

 cauline nematophores two on each internode of main stem, one close to the 

 axil of the pinna and the other near the proximal end of the internode. 



Gonosome. — Corbula with about ten pairs of leaflets ; leaflets broad, 

 united into a completely closed corbula, the distal margin of each carry- 

 ing numerous well-developed denticles, and projecting from the sides of 

 the corbula in the form of a pectinated ridge which is continued as a 

 free serrated crest beyond the roof; a spur-like denticle at the base of 

 each leaflet ; peduncle of corbula carrying a single hydrotheca. 



Off Tortugas, from a depth of 68 fathoms. 



The corbula of this species, with its pectinated ridges and crests, is a very 

 beautiful object, and affords a well-marked specific character. 



Aglaophenia apocarpa. 

 PI XXIV. Figs. 5-9. 

 TropJiosome. — Hydrocaulus attaining a height of about two inches, 

 simple, not fascicled ; pinnse alternate ; internodes of pinnae somewhat 

 bent backwards at their proximal end so as to give rise to a slight 

 angular bend at the point of junction of every two internodes. Hydro- 

 thecas deep ; margin with about nine deeply cut teeth, slightly everted ; 



