404 PROF. J. A. THOMSON AND MR. W. D. HENDERSON ON [Apr. 10, 



somewhat different, and no rods are pi-esent unless the side view 

 of the discs could be called rods. 



In another set of specimens very like those mentioned above 

 the polyps vaiy from 3-6-5 mm. in length. They are marked by 

 annulations and sometimes by longitudinal lines. The tentacles 

 are short, but the pinnules are arranged in three rows. The 

 spicules are small discs O'Ol mm. in diameter, somewhat pitted in 

 appearance. 



Locality. Zanzibar shore. Pi-eviously from Zanzibar, Red Sea. 



Olavularia MARC4ARiTiFERiE Thomsoii & Henderson. 



Numerous stiflf white polyps rise at right angles to a height of 

 6-7 mm. from narrow stolons (0-3-0"4 mm. across) spreading 

 over a flattened twig. The strands of the stolon may form a 

 network, but never coalesce into a membrane. The specimens 

 agree closely with C. 7n.argaritiferce, e. g. in the abundance of 

 interlocked capstan-like spicules (double clubs and double wheels), 

 0-04-0-07 by 0-02-0-04, with three or four large tubercles at 

 eacU end, in being broader orally than basally (0-6 at the base, 

 1-1 "3 mm. distally), in being often broader than the stolon. A 

 small portion of the upper end of the polyp is capable of 

 invagination along with the tentacles ; the expanded tentacles are 

 seen in a few forms as if rising on a nairower neck from Avithin 

 a broader funnel. There is thus the beginning of an interesting 

 distinction between a calycine portion and an anthocodial portion 

 which are separated by a slight constriction. This points on to 

 Synipodmm. There is a single I'ow of 8 or 9 short pinnules on 

 each side of the tentacles ; they are about 0"1 mm. in length. 



The specimen differs from that described as 0. margaritiferce 

 in having no spicules on the tentacles. The rest of the surface 

 has a gi'anular appearance due to the spicules. 



Locality. Chuaka. 



Previously recorded from Gulf of Manaar. 



Olavularia crosslandi, sp. n. (Plate XXX. fig. 6.) 



The stolon is a membranous plate. The genei-al colour is light 

 brown. 



The polyps are long and slender, the walls deeply marked by 

 longitudinal nairow grooves and broad white lidges. The length 

 of the polyps is about 5 mm., the breadth about 0-75. The 

 tentacles are 2'5-3 mm. in length. Many of the polyps have a 

 swelling just below the insertion of the tentacles, 1'2 mm. in width. 



The tentacles are flat and lanceolate, with the pinnules ari-anged 

 in two rows, but this appeai-ance may be due to the crowding of 

 the pinnules of one row. They leave a bare space on the oral as 

 well as on the aboral surface of the tentacles. The ^jinnules are 

 very short and bluntly conical, thereby differing very markedly 

 from G. garcice, which the colour and the longitudinal grooves at 

 first suggested. There are sevei^al noteworthy features in regard 



