554 



DR J. STUART THOMSON ON 



rudimentar werden. Die Polypen haben einen scharf gesonderten nicht retractilen 

 Kelch aufzuweisen, in welchen der obere Teil zuriickziehbar ist." 



Regarding Kukenthal : s revision and emendations there are elements of doubt as to 

 whether Gray's genera Nidalia and Bellonella are really identical, and that the genus 

 Gersemia as amended by Kukenthal has little in common with the original diagnosis 

 as given by Marenzeller, and whether certain species included by him under this 

 genus should really be placed there. 



As there does not exist a very complete knowledge of the anatomy of some of the 

 forms included under the name Nidalia or Bellonella, and as the systematic position 

 of these forms appears to be in a state of transition as shown even in the progressive 

 stages of Kukenthal's own work, I prefer to wait for further investigation. I place 

 my species among the Alcyonidse rather than as belonging to the Nephthyidse. The 

 characters of this form are so well marked as to render detailed comparison with allied 

 forms unnecessary. 



Locality, etc. : — " Pieter Faure," No. 18,831. St Francis Bay, Noors Kloof Point, 

 N.W. by W. l W. to N.W. by W. \ W. 8-12 miles. Depth, 23-35 fathoms. Nature 

 of bottom, fine sand and mud. 



Bellonella rubra, Brundin. 



Plate II. fig. 13; PI. III. figs. 21 a-c ; PL IV. fig. 43. 



This description is based on four specimens in all of which the polyps were almost 

 completely retracted. At first I thought that these were retracted specimens of 

 Melalcyonium clavatum, Pfeffer, but on closer examination they showed important 

 differences. 



The following measurements were taken : — 





Specimen A. 



Specimen B. 



Specimen C. 



Specimen D. 



Length of entire colony, .... 



Length of trunk, ...... 



Breadth of trunk at middle, .... 



Length of polyp-bearing part, 



Length of polyp-bearing part at middle, 



44"8 mm. 

 24-0 „ 

 11-0 „ 

 20-8 „ 

 10-0 „ 



33 5 mm. 

 16-0 „ 

 110 „ 

 17-5 „ 



8-8 „ 



22-0 mm. 



7-0 „ 

 13-0 „ 

 15-0 „ 

 12-0 „ 



2P0 mm. 



12-0 „ 

 6'5 „ 

 9-0 „ 

 6-5 „ 



The surface diameter of contracted polyps is about 2 mm. The distance of polyps 

 from one another is about 2 mm. 



The colonies are of a light crimson-rose colour, the polyp-bearing part having a 

 deeper colour than the trunk, which is sometimes almost white. The general shape of 

 the colony resembles that of a cut or lopped trunk of a tree, but with a rounded apex. 

 The base of the trunk sometimes expands into processes for attachment. Longitudinal 

 and transverse grooves sometimes occur on the surface of the trunk. 



