184 3. H. ASHWORTH. 



The pinnules on each side of the middle line of the tentacle are 

 arranged in three longitudinal rows, and they form also somewhat 

 oblique transverse rows of three pinnules rising from the oral towards 

 the aboral side of the tentacle (Fig. 3, D). When the tentacle is viewed 

 from the inner or oral aspect, all the pinnules are generally visible 

 (Fig. 3, B, D), but on the outer or aboral side of the tentacle only the 

 outer longitudinal row of each side is, as a rule, seen (Fig. 3, A, C). 

 The pinnules are often clearly separated into the two series of three 

 rows in each by a narrow area which extends along the middle line of 

 the inner face of the tentacle, from the base to within a short distance 

 of the tip (Fig. 3, D). This area, free from pinnules, may be *25 mm. 

 across, and may often be traced to within 1 mm. of the tip of the 

 tentacle. In other specimens, however, it is entirely obliterated, and 

 the median pinnules of the two series are in contact with each other, 

 at any rate at their bases. The width of this area varies, not only in 

 separate individuals, but in the different tentacles of the same 

 individual. These variations are probably due to the different degrees 

 of contraction of the tentacles on killing, and the condition in which 

 the free area is w r ell marked is seen only in those tentacles which have 

 been killed in an expanded condition. 



At the tip of the tentacle the pinnules are smaller than those in 

 the middle. They are arranged more or less in two series, one on each 

 side of the middle line of the tentacle, but three rows on each side are 

 not distinguishable ; at a distance of about 1 mm. from the tip of the 

 tentacle, however, the typical arrangement of two series, with three 

 rows of pinnules in each, is gradually assumed (Fig. 3, B). 



At the base of the tentacle the pinnules are much smaller but have 

 the typical arrangement, except in the case of one or two of the 

 proximal transverse rows. Here the pinnules appear to be in course 

 of formation, the outer ones being formed first, the inner ones 

 developing from without inwards (see Fig. 3, D). 



On looking at the tentacle from the outer side only the outermost 

 row of pinnules is usually visible. These, which are about twelve to 

 twenty in number on each side, are set close together and point 

 towards the tip of the tentacle (Fig. 3, A). At the tip of the tentacle 

 the arrangement of the pinnules may be well studied, and, as in 

 Alcyonium (Hickson, 1895), they are not paired (PI. XIX. Fig. 2). 

 The pinnules are conical elevations with rounded ends. Those in the 



