REPORT ON THE PENNATULIDA. 



which is the inner or concave side of the curve formed by the whole 



rachis, is referred to as the ventral mrface (Figs. 3 and 5); the opposite 

 or convex face (Figs. 1, 3, and -4) is the dorsal surface, while the sides are 

 referred to as right and left lateral surfaces respectively. 



The whole pen is of an ivory-white colour* except the stalk, 

 which is yellowish brown. The surface is covered with a slimy mucus, 

 and is in the living animal, according to both Forbes and Thomson,! 

 brilliantly phosphorescent. 



The term feather, which is often used to designate the rachia and 

 polypes together, calls to mind the fanciful narae Penna del pesce 

 inivone (feather of the peacock fish) given to Funiculina by the 

 Neapolitan fishermen, under which name it was described in 1757 by 

 Bohadsch, the discoverer of this very curious Sea-pen. 



Anatomical Desceiption. 



1. — The Stalk and Rachis — 



The stalk in the large specimen measures six inches in length. 

 Along its greater part it is cylindrical, with a diameter of 0-15 inch ; 

 toward the lower end it enlarges to 0-21 inch. The last |-in. is bent 

 rather sharply, nearly at right angles to the main axis (Fig. 1), and ends 

 in a blunt point. The upper part of the stalk diminishes gradually 

 in size, loses its cylindrical form and becomes quadrangular, the lateral 

 diameter slightly exceeding the dorso-ventral one. At the junction 

 of stalk and rachis the actual measurements are — lateral diameter, 

 0-13iu. ; dorso-ventral diameter, O'lOin. 



The rachis gradually increases in thickness in passing upwards 

 from its junction with the stalk; it also loses its quadrangular form 

 and becomes cylindrical. At about six inches from the top (Fig. 3), 

 at which point it attains its greatest size, the diameters are — lateral, 

 O'lSin. ; dorso-ventral, 0"17in. ; above this point it tapers rapidly to the 

 top. 



We have been unable to examine the internal structure of the 

 stalk and rachis, as the specimens were destined for museum purposes. 

 KoUiker I has shown that they are traversed along their whole 

 length by four main longitudinal canals (Fig. 3, m.), one dorsal, one 

 ventral, and two lateral, from which smaller canals arise forming a 

 rich network of nutrient vessels traversing the coenenchym, and com- 

 municating, as we shall see shortly, with the body-cavities of the 

 polypes. We have been able to confirm the existence of these main 

 canals, though we have not had an opportunity of tracing them along 

 their whole length. The smaller canals, with their openings into the 

 cavities of the polypes are shown in Plate II., Figs. 10 and 15, v. 



* Both Forbes (" Johnston's British Zoophytes." 2ud ed., 1847, p. 165) and 

 Thomson (" Depths of the Sea," 1873, p, 149j describe the Hviag Funiculina as 

 rose-coloured. 



t Forbes, loc. cit. Thomson, op. cit. J Op, cit., pp. 253-254, 



