20 THE VOYAGE OF H.M.S CHALLENGER. 



Omenakfiord, North Greenland, lat. 71° 71' N., long. 23° 58' W., depth 122 fathoms) 

 and U. magnijiora have been found militates a -priori against their identity. 



The Crinillum siedenburgii of Van der Hoeven is, as I have shown, the basal 

 part of a Pennatulid, and no doubt of an Umhellula, as the axis has the same form as 

 that of most Umhellulce. 



Habitat— Bmda. Sea, lat. 6° 40' S., long. 126° 47' E. Depth, 2700 fathoms. 



4. Umhellula leptocaulis, n. sp. (PI. IX. fig. 35). 



Decidedly bilateral. Calcareous needles pretty numerous in every part of the cutis, none 

 very large. Polyps disposed alternately, of a light brown colour, large, with thin sarcosoma. 

 Zooids scanty, on the rachis only, ventral, lateral, and dorsal. Stalk quadrangular, thin, 

 with thin sarcosoma. Axis quadrangular, with concave surfaces and blunt edges. 



Of this species I had at my disposal one smaller, perfect specimen (b), 150 mm. in 

 length, with three polyps; and the upper part of a larger one (a), with five polyps, con- 

 sisting of four fragments, and altogether 350 mm. in length. 



The stalk is remarkable for its thinness. In A it measured 0"85 mm. in diameter 

 below, and 0'34 to 0"37 mm. in its upper part. In B there was an end-bulb of 0"42 

 mm., and the average breadth of the rest of the stalk was 0"42 to 0"28 mm. 



In the polypiferous part the ventral side shows a small, keel-like rachis, which bears 

 the polyps on both sides, so that there is no larger free ventral space as in Umhellula 

 durissima and Umhellida giintheri. The ventral zooids are, therefore, very few, and form 

 only a small series on both sides of the keel. The lateral zooids are represented by a 

 few individuals only, and the dorsal are also few in number, and disposed on a small 

 dorsal free space between the polyps. 



The polyps, 27 to 30 mm. in length in A, are thin in their sarcosoma, and show the 

 same arrangement of the calcareous needles as in Umhellula giintheri, with this excep- 

 tion, that the needles of the tentacles are all disposed parallel to the longitudinal axis of 

 the stems of the tentacles. The needles of the polyps in A measure 0"43 to 0"54 mm. in 

 lengths and 0"027 mm. in breadth, and those of the tentacles 0"16 to 0'21 mm. Those 

 of the stalk measure in A O'll to 0"18 mm. in length, and 0"027 to 0"054 mm. in 

 breadth ; in B, 0'064 to O'lO mm. in length, and 0"027 to 0'064 mm. in breadth. The 

 needles in the lower part of the stem are of the common type, the shorter granulated 

 and warty, and broader the shorter they are. 



Habitat. — Station 181 , South Pacific Ocean, south-east of New Guinea, lat. 13° 50' S., 

 long. 151° 49' E. Depth, 2440 fathoms. Pved clay. August 25, 1874. 



5. Umhellula simplex, n. sp. (PI. IX. fig. 36). 



Decidedly bilateral. Calcareous needles numerous in every part of the cutis, none 

 very large. Polyps disposed alternately, colourless, small, rather hard. Zooids none. 



