REPORT ON THE PENNATULIDA. 27 



1. Alicroptilum 'wiUemdesi, n. sp. (PI. VII. fig. 27). 



Small, racliis longer than the stalk. Stalk with very incon.spicuous swellings. Polyp- 

 cells of two kinds, larger and smaller ; the larger, 2 '8 to 3 "4 mm. in length, alternate 

 pretty regularly with the smaller, the size of which is about O'S mm., and which are to be 

 regarded as belonging to developing polyps. Number of larger cells 1 2 ; underneath the 

 lowest, three smaller cells follow, visible with the naked eye, and three or four zooid-like 

 undeveloped polyps, which are only to be seen with the microscope. The polyps are the 

 only coloured parts of the polypidom, and have brownish stomachs, while the rest of their 

 bodies has a yellowish tint. 



Zooids flat, oval, 0"37 mm. long, without spines. 



Calcareous corpuscles of the form of needles, 0"86 mm. long on the rachis, and 

 decreasing to from O'OBO to 0'14 mm. and less on the stalk. 



Eachis broad, 070 mm. 



Stalk 0-45 to 0-48 mm. 



Length of the whole polypidom 65 mm., of the stalk 2.5 mm. 



Habitat. — One single specimen from Station 235, south of Yeddo, lat. 34° 7' N., long. 

 138° 0' E. Depth, 565 fathoms. Bottom temperature, 3°-3 C. Mud. June 4, 1875. 



Leptoptiluin, n. gen. 



Sea-pens of the family of Protoptilidse. Polyps with cells, sessile, disposed alternately 

 in one single row on each side of the racliis. Cells cylindrical, with eight long spines. 

 No real zooids, but a certain number of rudimentary polyps between each pair of the full- 

 grown individuals. Axis round, jaointed, and straight at both ends. Calcareous corpuscles 

 in the stalk, rachis, the cells, and the tentacles of the polyps 



1. Leptoptilum gracile, n. sp. (PI. VII. fig. 28). 



Small, rachis longer than the stalk. 



Stalk with a small enlargement at its upper end, and a little end-bulb. 



Polyp-ceUs 2 to 3 mm. long, and 0'85 mm. broad, with eight well-developed spines at 

 their opening, but disposed in such a manner that many of them appear to be opposite, which 

 is in reality nowhere the case. Another peculiar feature is that the size of the polyp-cells 

 does not decrease regularly towards both ends of the rachis, as is usually the case, but 

 that- in the centre smaller and larger ceUs are found without any rule in their distribution. 



The polyps are the only coloured part of this sea-pen, their stomachs being brown, and 

 the other parts yellow. The axis of the tentacles bears a row of calcareous needles 

 O'll mm. in length. 



The rudimentary polyps lie two to five in number, and 0'16 to 0'32 mm. ami 

 upwards in size, between each pair of developed polyps. They possess similar cells, liut 



