68 



MR JAMES RITCHIE : SUPPLEMENTARY REPORT ON 



Antennopsis scotiae, Ritchie, 1907^^1 



An additional colony of this species from the locality from which it was originally 

 recorded enables me to amplify the diagnosis already given and to add a description of 

 the gonosome. The new colony is of the same height as the larger of our earlier speci- 

 mens, 9 cm., but it bears more branches and is altogether in better condition, although 

 here also the hydroclades are in many places wanting. Branches are frequent, but are 

 very irregular in position. They may bear secondary branches which are long, of uniform 

 thickness, and are seldom branched. The stem and branches are composed of a thick 

 bundle of tubes with transparent walls and without nodes. From short processes on the 

 outermost of these the hydroclades spring, following one another on the same tube at a 



Fig. 8. — Antennopsis scotia: (a) Portion of hydroclade showing thecate and atheeate intei-nodes, and arrangement of 



nematothecw. x 65. {h) Gonotlieca. x 4.1. 



distance of some 073 mm., and thus forming a close-set coat round the branches. In 

 consequence of the delicacy of the hydrothecal margins a perfect hydrotheca is rare, but 

 where such occurs it shows a slight widening at the mouth. 



An important addition has to be made to the previous description of the trophosome 

 as regards the number of the nematophores accompanying the hydrotheca. Besides tlie 

 median proximal nematophore and the lateral pair surmounting the processes which run 

 alongside the hydrotheca, there is a supplementary lateral pair, the individuals of whicli, 

 one on each side of the hydrotheca, rest on the upper surface of the lateral process 

 almost in the corner formed between it and the internode (fig. 8). These nematophores, 

 although of similar structure to, are considerably smaller than, the others, and are so 

 delicate that they are frequently absent, their former position being marked only by a 

 small opening in the lateral process. They correspond exactly to the supplementary 

 nematophores described in Antenella quadviaurita of the present paper. 



The atheeate internodes show more variation than in the former specimens, 

 their length in many cases preventing the margin of a hydrotheca from reaching 

 the level of the proximal end of the succeeding tliecate internode. Only two 



(ROY. SOC. EDIN. TRANS., VOL. XLVII., 90.) 



