108 THE VOYAGE OF H.M.S. CHALLENGER. 



others bear one or two lateral secondary pinnules, indicating a transition to the 

 bipinnate type. 



Two or three of the branches in the lower part of the specimen have been broken near 

 the tip, the lost portion being represented by a new and more slender growth from the 

 point of fracture. 



The polyps and coenenchyma are well preserved all over the specimen. Those polyps 

 situated on the stem, particularly in the lower portion, appear to have undergone con- 

 siderable degeneration and are altogether smaller and less prominent than those on the 

 branchlets and pinnules. They are arranged somewhat irregularly, evidently not in a single 

 longitudinal row, but apparently all are confined to the anterior and lateral surfaces. 



The polyps on the pinnules and branchlets are all situated on the anterior surface, 

 forming a regular longitudinal series. On one simple pinnule, 4 cm. in length, there are 

 thirty polyps, all similar in size and equidistant, with the exception of two at the base which 

 are rather smaller and more isolated. In other portions of the colony, particularly near 

 the apex, the zooids are unequal in size, owing to the fact that by a process of budding 

 new zooids are added at various points along a branchlet. In this respect there is an 

 approach to the arrangement of zooids in Leiopathes, but the irregularity in size is 

 never so well marked as in that genus, and the irregularity is here confined to more 

 limited areas. In zooids preserved with the mouth open, the aperture has a distinct 

 crenate outline and there is a partial eversion of the stornodasum, each fold of which is 

 limited by two mesenteries. In such cases (PL XIII. fig. 4) the mouth has not the 

 slit-like lumen corresponding to that of the middle portion of the stomodasum, but the 

 aperture is wide and rounded, with a crenate margin. The zooids are irregular in shape, 

 but in a typical case there is always a pronounced elongation in the transverse axis. 

 The zooids on the thicker branches are usually smaller than the others, and have a 

 rounded outline, and in certain cases young zooids have a similar contour, due 

 possibly to the limited areas in which they are at first formed. With these excej^tions 

 the zooids invariably show an elongation in the direction of a branch, which causes the 

 tentacles to be arranged in two rows of three each. There is no marked difference 

 in size between the tentacles, all are (in spirit preparations) thick and subcylindrical, 

 with a blunt apex. Lacaze Duthiers, who has studied living specimens, states 

 that the tentacles are never elongate as in many other forms, Parantipathes larix for 

 example. In expanded polyps the diameter across the tentacles never exceed 2^ 

 diameters of the pinnule on which they are situated. His figures of the polyps in this 

 species (45, pi. i. figs. 3 and 4) represent the rounded type which I have observed on the 

 stronger branches. The latter figure shows a number of polyps contracted, so that the 

 tentacles are pressed down close over the mouth — a condition approaching that which 

 occurs in those Actiniaria having a well-developed sphincter muscle. I have not 

 observed such a contraction in specimens of this or of any other member of the Anti- 



