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



The polyps begin below with a long row of undeveloped individuals the real length 

 of which cannot be ascertained owing to the bad state of preservation of this part of the 

 polypidom. The developed polyj^s measure 1'2 to 3 "2 mm. in length, are rather crowded, 

 and so placed that smaller and larger are intermingled without any rule. Colour of the 

 polyps brown, with the exception of the tentacles which are colourless, and contain 

 calcareous needles of 0'15 mm. in length. Polyp-cells with strong colourless needles of 

 0'5 mm. 



Eachis quadrangular, 076 mm. broad, brown on all four sides, from, the colour of the 

 epithelium of the longitudinal canals. Sarcosoma in small c[uantity, with some needles 

 in its dorsal side. 



Habitat. — One single specimen from Station 192, south-east of Ceram, west of New 

 Guinea, lat. 5° 42' S., long. 132° 25' E. Depth, 129 fathoms. Mud. September 

 26, 1874. 



Scleroptilum, n. gen. 



Sea-pens of the family Protoptilidse. Polyps without cells, sessile with broad bases, 

 disposed on each side of the rachis in a single row. Zooids dorsal, apparently in one row. 

 Axis round. Calcareous corpuscles of large .size, abundant in the polyps and their ten- 

 tacles, and in the sarcosoma of the rachis ; those of the stalk numerous, but smaller. 



1. Scleroptilum grandijlorum, n. sp. (PI. VII. fig. 29). 



Calcareous corpuscles in the smaller branches of the tentacles very few in number. 

 Polyi^idom of medium size, uncoloured. Rachis longer than the stalk. Stalk, with an 

 upper swelling, and an end-bulb. Polyps usually disposed in pairs, apparently opposite, 

 while, on a closer ins|)ection, it becomes evident that the two polyps of a pair never lie 

 on the same level ; nevertheless, regular alternation does not take place, the more so 

 as in many places a single polyp is interposed between two pairs. The intermediate 

 polyps, which are smaller than the others, may be looked upon as indications of new 

 developing pairs, as we have seen that in several genera of the Protoptilidce young polyps 

 are developed between the old ones. 



The single polyps are large and hard and stilf, from the great number of strong 

 calcareous needles in their sarcosoma. Their length is about 5 mm.,— with extended 

 tentacles, 6 mm. ; and their breadth at the base 3 mm., and higher up, just below the 

 tentacles, 1"5 mm. Nearly all are curved in such a manner that the tentaculiferous 

 part is bent upwards ; in some instances the curve is even stronger, and then the 

 tentacles look towards the stalk. 



The zooids measure at their base 0'42 mm., and are small conical prominences, with 

 an elevation of not more than 0"2 mm. They are all dorsal, and form one single row, 

 which is so disjjosed that one portion lies on the right, and the other on the left of the 



