32 HALOPTETtlS. 



Flumularia geminata. 

 PL XX. Fiffs. 1-4. 



Troj)hosome. — Stem attaining a height of about one inch, dichotomously 

 branched ; internodes towards the distal extremity of the branch alternately 

 longer and shorter ; each shorter internode carrying near its middle a 

 hj'drotheca, on each side of which springs an ultimate ramulus, also com- 

 posed of alternately longer and shorter internodes ; each shorter one 

 carrying a hydrotheca. Hydrothecte campanulate with slightly everted 

 niai'gin, free for about its distal half Lateral nematophores borne each 

 on a strong tooth-like process of the internode ; mesial nematophores 

 carried upon both the hydrothecal and the intervening internodes. 



Gonosome. — Gonangia pyriform, borne on short two-jointed peduncles 

 which sj^ring from the mesial line immediately below the hydrotheca, the 

 narrow proximal end of the gonangia carrying a nematophore on each 

 side. 



Off' Sand Key, from a depth of 120 fathoms. 



Plmmtlaria geminata is a very remarkable form ; the ultimate ramuli given 

 off in regular pairs from the principal branches confer upon it a very 

 striking aspect. All these pairs of I'amuli are directed towards one side 

 of the branch from which they spring. The proximal joint of each hydro- 

 theca-bearing internode in the ultimate ramuli is very oblique, the distal 

 one transverse. This internode carries a single mesial nematophore, which 

 is situated at the proximal side of the hydrotheca, while each intervening 

 internode of the ramulus carries three. In the main branches each hydro- 

 theca-bearing internode carries also a nematophore at the distal side of 

 the hydrotheca, while four nematophores are borne on every intervening 

 internode.* 



HALOPTERIS Allman nov. gen. 



Generic Character. Tropho.wme. — Hydrosoma pinnate plumose; stem 

 and pinna3 divided into internodes. H^'drothecEe adnate to side of pinnte, 

 imilatei-al. A pair of nematophores flanking the hydrotheca, one on 

 each side, and adnate to it. Mesial nematophores two (or more), not 

 adnate to the hydrotheca, fixed, monothalamic, with an oblique aperture 

 continued into a lateral slit. 



Gonosome not known. 



* See Addenda, p. 56. 



