68 DR. W. RAE SHEIUUFFS ON EVOLUTION 



17. Dendronephthya pumilio (Studer). 



Described by Studer in Ann. Mag. Nat. Hist. (6) vol. i. pp. 70- 

 71 (1888). 



Diagnosis: — Umbellate; branches in rounded bunches closely 

 packed ; outline uniform ; general shape flat to globose ; polyps 

 on the terminal twigs; polyp stalks long; supporting bundle 

 very strong; point spicules about 5 pairs, the uppermost 

 elongated ; no crown ; grade IV. ; spicules : lower coi-tex has 

 thick, bent, thorny spindles but no distinct stars ; colour : 

 generally yellowish white, polyps dark red, the tentacles densely 

 crowded with minute rod-like reddish spicules. 



Anthocodial Grade and Formula :-^ 



lY. = I + 4p + 0Cr+ very sti^ong iS.B. 



Descriptive Notes : — 



1. Colony as a ivhole. Four interesting sjjecimens at dift'erent 

 stages of growth, the largest having the following dimensions: — 

 Total height 16 cm., height of sterile stalk 6-5 cm., breadth of 

 polyparium 9"5cm. The colony is very markedly umbellate in 

 its largest forms, but less so in the younger forms, which tend 

 to be much flattened. 



2. Branching. The branches form rounded bunches, closely 

 packed together and forming in the larger colonies a markedly 

 uniform contour. The general shape varies from flat to globose, 

 and I do not think that any importance can be attached to 

 this. 



3. Colouring. Yellow white, polyps Text-fig. 24. 

 dark red. 



4. Polyp stalks long. /**'. 



5. Pohji^s arranged on the terminal 

 twigs. 



6. Poly20 spicules. The anthocodial 

 ai-mature is marked by the elongation of 

 one or both of the terminal spicules of 

 each point, the others, to the number 

 of 2 or 3 pairs, being markedly sub- 

 ordinate. This is my grade TV. There 

 is no crown. 



The tentacles are long and heavily 

 armoured, bearing dorsally a crowd, 

 sometimes bilinear, of minute oval or D. pumilio ^iwA. 



rod-like reddish spicules. 



The supporting bundle is very strong, the largest spindle often 

 projecting for 1 mm. The spicules are finely and thickly spmose, 

 and often shoAv smooth points. In many cases one polyp and its 

 supporting bundle may be seen to predominate markedly over 

 the others in the group. 



7. Other spicules. The spicules of the lower cortex are mostly 

 thick spindles, usually bent, and densely covered with strong, 



