56 



P.R. PUGH 



B 



Fig. 5 Bargmannia elongata. A. Young tentilla with stenoteles (st) at proximal end of cnidoband (magn. 50x); B. Part of siphosome showing three 

 siphosomal tentacles (t) and several buds (b) (magn. 16x); C. Male gonophores (magn. 30x). 



mesogloea. At its base the lower nerve tract can be seen to leave its 

 proximity and to continue down beneath the ventral surface of the 

 nectophore to reach the ostium. The short pedicular canal (Figure 

 2B, pedc) extends through the mesogloea, from the base of the 

 pallial canal, to the nectosac. There it gives rise to only the dorsal and 

 ventral radial canals. The lateral canals arise separately, but in close 

 proximity to each other, from the dorsal canal, and initially are 

 directed toward the apico-lateral margins of the nectosac. They then 

 continue down the lateral margins of the nectosac and, although their 

 courses show undulations (Figures 1C, 2C), they are merely follow- 

 ing the dorso-ventral undulations in the nectosac itself; the latter 

 being a preservation artefact. 



The youngest nectophores (Figure 3A, B) typically show the 

 absence of a median thrust block, and the apico-lateral margins are 

 demarcated by the apico- and infra-lateral ridges. The basal portions 

 of the apico-lateral ridges are particularly well marked, and the inner 

 branches are distinctly broadened, often appearing almost bifurcate 

 at their basal ends, which lie just above the ostium (Figure 3A). 

 There are two short tracts of cells extending out from the lateral 

 processes of the ostium just ventral to the outer branch of the apico- 

 lateral ridges. These could not be discerned in the mature nectophores. 



Bract (Figure 4). The bracts are extremely delicate, foliaceous 

 structures, the largest of which measures 9 mm in length. The dorsal 



surface is slightly convex, the ventral one slightly concave. For many 

 the proximal region is bent up dorsally, or one side is folded over the 

 other resulting in a distinct asymmetry. The bracteal canal extends, 

 approximately in the mid-line and in close proximity to the ventral 

 wall, to about four- fifths the length of the bract. The distal end of the 

 bract is slightly truncate and bears two lateral processes, which vary 

 in shape from merely rounded corners to distinct teeth. The region 

 between them usually is roundly pointed. Additional processes may 

 be present on the lateral margins of the bract. Again these can form 

 distinct teeth, but quite often are indiscernible. The maximum 

 number of lateral processes found was two on one side, and one on 

 the other. The distal half of the dorsal side of the bract is dotted with 

 distinctive patches of small round ectodermal cells. These patches 

 are densely packed on the smallest bracts; but more spread out on the 

 larger ones, where some patches have been lost by abrasion. These 

 cells probably are sites of bioluminescence. 



GASTROZOOID AND TENTACLE. The larger gastrozooids in the 

 Alvin material measured up to 10 mm in length. They are brown in 

 colour, in their preserved state, and are comprised of a short, narrow 

 basigaster, to the base of which the tentacle is attached; a large, 

 expanded stomach, the inside of which is covered with thickened 

 patches of endodermal cells; and a long proboscis, with longitudinal 

 endodermal hepatic stripes. Several younger, smaller gastrozooids 



