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



5. Pennatula sulcata, n. sp. (PI. II. figs. 3, 4). 



General character of Pennatula rubra and Pennatula Jimhriata ; colourless, with a 

 deep groove on the dorsal side of the rachis ; the leaves are very numerous ; ventral and 

 lateral zooids are present, the latter of which are also visible on the dorsal aspect of the 

 rachis. Besides these there is a long row of zooids at the dorsal end of the polypiferous 

 margin of the leaves. 



Feather more than twice the length of the stalk. 



Pinnules thin, transparent, closely set, twenty-six to twenty-seven in numher, 

 lanceolate or triangular. Base of the pinnule attached transversly to the rachis. Ventral 

 and dorsal margin straight, the latter beset with one row of polyp-cells, alternating so as 

 to produce the appearance of two rows, especially near the dorsal end of the border. 

 The polypiferous margin of each pinnule ends in a long narrow ridge, which runs 

 obliquely upon the dorsal side of the rachis, as far as the base of the next pinnule. This 

 ridge is merely a single row of small zooids about twenty-seven in number, and of the size 

 of 0"10 to 0'12 mm., which I call the zooids of the dorsal margin of the pinnules. 



Polyp-cells small, crowded, twenty-four to twenty-six on the larger pinnules ; and 

 pretty well separated, with eight strong spines. 



Eachis with a groove on its dorsal side, which begins shallow between the lowest 

 pinnules, assumes a depth of 3 mm. toward the middle of the feather, and runs out at its 

 upper end. This groove is narrow where it is deepest, and bordered by sharp whitish lips. 

 The calcareous axis lies inside at the bottom of the groove, and shines through the thin integu- 

 ment as a white streak. The ventral side of the rachis is covered on its sides by small zooids, 

 while the middle line is smooth. These ventral zooids are small wartlilie or conical bodies, 

 0'2 mm. in breadth, aU of one kind with this exception only, that those near the pinnules 

 have their calcareous needles projecting, and resemble small spines, whilst the others are 

 rather rounded j)rotuberances. These zooids are continuous between the pinnules with very 

 numerous lateral zooids of rounded form, which run up to the dorsal aspect of the rachis, and 

 reach as far as the ridges of the pinnules described above, on the side of which they end 

 with a pointed train. The stalk is short, enlarged in its upper part, and pointed at the end. 



With regard to the internal structure I have only to make the following remarks : — The 

 eggs are found in the leaves, and, as it appears, also in the stalk, as in Pennatula rubra, 

 if we may judge from the fact that the stalk contains on both sides a crowded mass of 

 eggs along the attachment of the pinnules. Calcareous corpuscles are found in the whole 

 integument. In the polyps short stout needles of O'll to 0'20 mm. lie in the stem of the 

 tentacles. The polyp-cells contain needles of 0'86 mm. maximum length, and 0"032 mm. 

 breadth. Those of the lateral and ventral zooids are numerous but smaller, and those of the 

 zooids of the pinnules are smallest, measuring only 0"081 to 0"10 mm. in length. Besides 

 these needles the rachis contains none except at the ventral side, where needles of '050 

 to 0"080 mm. are found in the lips which border the longitudinal groove. 



