1906.] ALCYONARIANS FROM ZANZIBAR. 411 



diameter of 11 mm. ; the polyps are 9-15 mm. iu length, 1-2- 

 2 mm. m breadth, with tentacles 6-5-8 mm. in length and 1*5 mm. 

 in breadth. A few young polyps are present among the older 

 polyps, and have an average length of 1-9 mm. and an average 

 width of 0-5 mm. On their small tentacles, however, from 6-7 

 pair's of pinnules may be seen. 



The tentacles in the older polyps are long and slender, with the 

 middle line free throughout its entire length on the abox'al surface. 

 The long and slender pinnules are arranged in 2-3 rows on either 

 side of the middle line. Between 30 and 40 were counted on one 

 row. There are abundant calcareous coi-puscles of minute size. 

 Numerous zoochlorellpe ai-e also present throughout. 



X. umhellata appeal's to be a very variable species if we extend 

 it to include those forms with not more than 3 rows of very long 

 and numei'ous pinnules, with tongue-like flattened free axis. 



In another specimen the polyps were from 5-11 mm. in length 

 by 1-5 mm. in breadth, with thin transparent walls, with spherical 

 calcareous bodies. The tentacles are long in comparison to the 

 length of the polyp, for they vary from 6-5-7 mm. in a polyp which 

 measures 11 mm., and they may be even longer than the polyps. 



The long and slender pinnules (1-4 mm. long by 0-15 mm. wide) 

 are arranged in Uoo or three rows on either side of the middle 

 line, leaving on both sui-faces a free space which i-uns the whole 

 length of the tentacle, and giving a fine feather-like appearance 

 to the tentacle. 



In the younger polyps, which measure about 3-3 mm. in height, 

 the tentacles reach a length of 2-3 mm., and have the pinnules 

 arranged in 3 rows, in the outei'most of which tliei'e ai'e from 7-9 

 pinnules. Thei'e are niuiierous spherical zoochlorella?. 



Another set of specimens (from Chuaka, E. Zanzibar) were 

 characterised by the vei'y long polyps (12-25 mm.), the flatness of 

 the tentacles, and the delicate triangular pinnules in five rows proxi- 

 mally and three rows distally with 24-26 in each row. 



Another specimen, which when living was white with yellow- 

 brown tentacles, was found growing over nullipore branches. 

 The stalk is firm and has an average length of 11 mm., and an 

 average breadth at the upper end of 4 mm. The polyps are thin- 

 walled and ti'ansparent, thickly placed on the crown, from 5-6 mm. 

 in length, with an average width of 0-8 mm. The tentacles are 

 very feathery in appearance, and vary in length from 2-3-2 mm., 

 and have a maximum diameter of 1 mm. 



The pinnules ai-e ai'i'anged in four I'ows on each side of the 

 middle line, leaving a free space on both the oral and the aboral 

 surface. In the outer row of pinnides the number varies from 

 14-18, but 17 is the commonest number. 



There are very numerous zoochlorellfe with a diameter of 

 about 0-01 mm., and there are also calcareous corpuscles. 



Locality. Wasin Channel, 10 fathoms ; previously recorded 

 from New Britain and from the Red Sea. 



