PENNATULIDA DREDGED BY- H. M.S. "TRITON." 143 



and extending a short distance below them; zooids of upper part of rachis 

 much the largest, and each provided with a tentacle bearing a double row of 

 pinnules ; zooids of lower part of rachis are smaller, — they may have tentacles, 

 but these do not bear more than a single pinnule. Stem cylindrical along the 

 greater part of its length, becoming quadrangular in the terminal dilated part. 

 No calcareous spicules at any part of the colony. 



Habitat. — Station 11 ; depth 555 fathoms. 



External Characters. — A single specimen of this species was obtained 

 with the trawl. This specimen, which is in perfect condition, is represented 

 of the natural size, and from the dorsal surface in PL XXV. fig. 29. It has a 

 total length of 290 mm., of which the upper 26 mm. are expanded to form the 

 club-shaped rachis. This ends above in a blunt point (fig. 30), and is widest about 

 the middle of its length, where it measures 6 mm. from side to side, and 5 mm. 

 from the dorsal to the ventral surface. 



The rachis bears the polyps on the upper two-thirds of its length, and below 

 the lowest polyp tapers somewhat rapidly, and passes without any sharp line of 

 demarcation into the stalk. 



The stalk is cylindrical and very slender, with a diameter about the middle 

 of its length of 0*8 mm. At its lower end it presents a distinct enlargement, 

 35 mm. long and 3*5 mm. in diameter. For the greater part of its length the 

 stalk is extremely flexible, so much so that it can readily be coiled in circles of 

 5 mm. diameter without the slightest danger of breaking. 



The stem or calcareous axis is cylindrical along the greater part of the 

 length of the stalk, with an average diameter of 0*5 mm. Shortly before 

 reaching the terminal dilatation of the stalk the stem enlarges somewhat 

 suddenly to 9 mm. in diameter, becoming at the same time quadrangular in 

 shape, and very much more rigid than in the upper part. In the terminal 

 dilatation it gradually tapers towards the lower end. 



The polyps, which are confined to the upper 18 mm. of the rachis (figs. 29 

 and 30) are 13 in number, and gradually increase in size from above down- 

 wards. They are inserted on all sides of the rachis, with the exception of a 

 narrow strip 1*5 mm. wide along the mid-ventral surface (fig. 30), and even this 

 is somewhat encroached upon by the lowest polyps. 



It is difficult to make out any definite plan of arrangement of the polyps. 

 Commencing at the top, the first polyp, which is the smallest of the lot, is 

 inserted in the left latero-dorsal surface just below the apex. The second 

 polyp is placed on the right latero-dorsal surface, a little way below the first. 

 Then comes a rather irregular whorl of six polyps, of which two are dorsal, 

 two lateral, and two latero- ventral ; and finally a lower whorl of five polyps, 

 the largest of all, of which one is mid-dorsal, two lateral, and two latero-ventral, 

 the left one of the last pair almost reaching the mid-ventral line. 



VOL. XXXII. PAKT I. 2A 



