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



the tentacles are simple and have no calcareous needles. Between these rudimentary 

 individuals and the full-grown polyi^s many intermediate stages may be found, and I 

 have no doubt that this sea-pen grows not only at the end, but also by the formation of 

 new individuals between the old ones. 



The calcareous corpuscles are very numerous in the cells, and in the integument of 

 the rachis, and have the form of long needles 0-35 mm. and upwards in length. On 

 the stalk the needles are also very numerous, but they diminish gradually in size, and 

 measure only 38 to 58 /x in its lower parts. In the end-bulb itself the muscular 

 layer contains the same small oval bodies of 3 to 15 /a, which have been described in 

 the genus Antlioptilum. 



In the axis radiating fibres are wanting, and are represented by the same oval plates, 

 which I have described in other Pennatulida. 



Measurement of the largest specimen — 



Length, of tlie whole, 



75 mm. 



Length of the stalk, 



23 



Breadth of the stalk above and below. 



0-58 



Breadth of the rachis, 



0-23-0-3'l 



Breadth of the axis. 



0-20 



Ilahitat. — Several weU-preserved specimens from Station 169, north-east of New 

 Zealand, lat. 37° 36' S., long. 179° 24' E. Depth, 700 fathoms. Bottom temperature, 

 4° -2 C. Grey ooze. 10th July 1874. 



Protoptilum, Koll. 



1. Protoptilum aherrans, n. sp. (PI. VIII. fig. 30). 



General appearance of Protoptilum carpenteri, Koll. Polyps larger, disposed in one 

 row only on each side of the rachis. Polyp-ceUs truncate at their upper end, without 

 spines. Zooids dorsal, lateral, and ventral, larger than in Protoptilum carpenteri. 

 Eacliis with a swelling in which the sexual products are found, in the lower part, in the 

 region of the undeveloped polyjDS. 



Polyps disposed, partly alternately, partly nearly opposite, forming in general a 

 single row on each side, but in some places shomng a tendency to an arrangement in 

 series of two ; polyp-cells of the form of a cornucopia, 2-85 mm. long, and 1-14 mm. wide 

 at the opening. Zooids of the form of the polyp-cells, 0'57 to I'O mm., with cells like 

 the polyps. The number of zooids is much more numerous than that of the polyps, and 

 they are placed without any apparent rule except at the lowest, thickest part of the rachis, 

 where the zooids alternate with the here rudimentary polyps in such a manner that one 

 dorsal and one ventral zooid is placed between two polyps. 



Eachis, 0-85 mm. broad in the upper parts, increasing below to 17 mm. and 2'0 mm. 



