ON THE ALCYONARIANS. 



two opposite sides of the branches, although by no means confined to these. They are 

 not wholly retracted, but protrude from the surface of the ccenenchyma as small 

 roundish warts surrounded by a gently sloping spicular dome, which rises gradually to 

 form a very slight lip around the polyp aperture. 



The spicules, which are whitish and translucent, are of three main types, (a) Most 

 abundant are long narrow spindles, e.g. 075 x 0'06, 07 x 0'05 mm., covered with warty 

 tubercles, which are frequently produced into blunt spines. The spines show a marked 

 tendency to unilateral development, being often more prominent and more numerous on 

 one side of the spindle, (b) Less abundant are scaphoid forms, e.g. 07 x 0'12, 0'4 x 0'06 

 mm. (c) There are also some forms which approach the ' club ' type and differ greatly in 

 size, e.g. 0'45 x 012, 0'25 x 0'06 mm. Their heads are covered with long blunt pro- 

 cesses, similar to the blunt spines of the spindles, and these are sometimes continued 

 down the ' handle ' of the club. Both the ' scaphoids ' and the ' clubs ' are readily 

 derivable from the spindle type. 



We have named this new species G. studeri after Prof. TH. STUDER, joint-author of 

 the Challenger Report on Alcyonarians. 



Locality. Station 81 ; lat. 18 26' S., long. 37 58' W. ; 40 to 50 fathoms. 



Family UMBELLULIM. 

 Umbellula durissima, Kolliker, PI. I. fig. 5. 



About twenty specimens of this beautiful form were obtained from one locality, 

 from a depth of 1742 fathoms (April 13, 1904). Only one specimen was obtained by 

 the Challenger expedition, and that much younger and smaller than the best of the 

 Scotia specimens. 



The following total length measurements were taken : 50, 45, 42, 37, 34, 32, 22, 

 20, 18, 17 cm. The heads vary from 2'8 cm. in height and breadth to 17 in height 

 by 0'5 in breadth. The stalk is very slender in proportion to the head, and the follow- 

 ing breadth measurements were taken : 3*5 mm. almost at the base and 1 mm. near 

 the top of the largest specimen ; 1*5 mm. at the base and 0'5 mm. near the top of the 

 smallest specimen. 



There is considerable diversity in the number of polyps thus one head had 9, one 

 had 7, five had 6, one had 5, and four had 3 polyps. The colouring of the polyps is 

 exceptionally beautiful a milky blue fading basally into white ; the tentacles are 

 chocolate brown. Eight vertical rows of rod-like spicules extend up the surface of the 

 polyps and are continued into the tentacles. The largest polyps measure 15 mm. by 

 8 mm., not including the tentacles, which are 15 mm. in length. The minute siphono- 

 zooids are exceedingly numerous, covering the whole ventral surface of the head except 

 a narrow median ridge, and also extending in bands between the bases of the polyps or 

 autozooids. The bluish colour was not noticed in the Challenger specimen, and 

 seems to be gradually fading in those under our observation. 



(ROY. soc. EDIN. TRANS., VOL. XLI., 859.) 



