PTEROBRANCHIA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 411 



unnecessary. Most of the pieces of material show no brandling, but resemble the 

 piece of which a photographic reproduction is shown in text-fig. 1, A. 



The surface of the colony appears rough, and, if the ostia or openings of the tubes 

 are not clearly visible, does not differ much from the surface presented when a piece 

 is broken across (text-fig. 1, D and E). But in sheltered situations, as between the 

 branches of a piece of colony, such as is shown in PL I. figs. 1, 4, there are blunt 



-..-. 



TEXT-FIB. 1. Pliritciiiraphie reproduction "f pieo", nf n-Lmy f ''. <////<///)-///s ; nf the natural size. A, a piece broader at 

 the free end (uppermost in the 1 ligurc) limn at Ilir basal mil, showing no branches : I!, a piece sliuwini; a branching inti> 

 two ; 0, a liingitiicliii.il median section nt'a piece of colony ; I> ami E. transverse sections tlm>nli a piece' nf colony. The 

 darker areas are tin' tnliiilar spaces occupied by the zuciids, the white peel are m , shell incliul"! in llir 



coenoecial substance. 



brownish processes or "spines" projecting to an extent of 3 mm. beyond the general 

 surface. Inspection shows that these are really the projecting lips of the inhabited 

 tubes, one to each tube, similar to the lips that occur on the surface of a piece of 

 C. nigrescens (07, pi. iv. fig. 1 1 ), but differing in being less regular in form. These spines 

 are built up by the superposition of solid caps of coenojcial substance upon the summit 

 of pre-existing spines, just as arc- the long spines of species of Cephalodiscus such as 

 C. dodecalophiis, C. }i(i</<ix<n/i (07, pi. iv. tig. 21), and C. </ili-lirixti M'>, pi. iii. tins. 9, 

 10, 11), but they differ in not exceeding a length of 3 mm., and in being restricted in 



(HOY. soc. EDIN. TRANS., TOL. MIX, '>'.',>. ) 



