438 PROF. J. A. TnOMSOX AND MR. W. D. HENDERSOX ON [Apr. 10, 



canals, and in having a slightly flattened axis. It differs from it 

 in having 66 polyps on a pinnule instead of 40-44, in having 

 2-4 rows of polyps instead of one row twisted so as to appear 

 like two, and in having a different disposition of zooids. 

 Locality. Ohuaka Bay, shore, lowest tide. 



Family Pennatulid^e. 



Subfamily PTEROEiDiNiE. 



Pteroeides brachycaulojST Kolliker. (Plate XXYl. fig. 3.) 



Belonging to this species there are several large specimens with a 



short rachis and a large spindle-shaped enlargement on the stalk. 



millims. 



Length of pinmde-bearing portion 170 



Breadth of pinnule-bearing portion 80 



Length of stalk 50 



On the rachis there is a broad bare space on the prorachidial 

 surface ; the corresponding part on the nietarachidial aspect is 

 hidden by the edges of the pinnules. 



The colour is creamy with irregular patches and streaks of a 

 pui'plish-blue. 



The pinnules are 34 in number on each si le, with two or three 

 rudimentary forms at the lower end of the rachis. A well- 

 developed pinnule has a breadth of 44 mm. and a height of 

 31 mm., and is supported by 16-18 rays. 



The zooid-plate is median, leaving a crescent free from polyps 

 at the basal insertion. 



Locality. Kokotoni Harbour, West Coast of Zanzibar, 5 fathoms. 

 Previously recorded from the Philippines. 



Pteroeides rigidum, sp. n. (Plate XXVI. figs. 1 & 2.) 

 Two specimens of a stiff colony very long in proportion to its 

 breadth, apparently of a bluish -brown colour. As the zooid- 

 plate is large and basal and the length of the rachis is at least 

 eight times its breadth, the position of this species should be in 

 Kolliker's group Pt. argenteum, but it does not agree with any of 

 the forms there described. 



The following measui'ements were taken fi'om the stronger of 

 the two specimens : — 



millims. 



Total length of colony 230 



Length of pinnule-bearing part 137 



Length of stalk 93 



Maximum breadth of pinnule- bearing part 17 



• Breadth of the middle of the stalk 8 



Breadth of the swelling at the top of the stalk 10 



Length of the swelling at the top of the stalk 15 



Breadth of the pinnule halfway up 8 



Height of the pinnule halfway up 5 



Distance between pinnules 1 •5-4"5 



Breadth of the axis near the base 4 



